# Ocean Facts

Answers to your questions about our oceans and coasts.

- What are nature-based solutions? Infrastructure projects that intentionally use natural and nature-based habitats and processes to reduce risks and deliver multiple benefits are referred to as nature-based solutions. Continue reading &rarr;
- What is the Atlantic Meridional Overturning Circulation (AMOC)? The ocean’s water is constantly circulated by currents. Tidal currents occur close to shore and are influenced by the sun and moon. Surface currents are influenced by the wind. However, other, much slower currents that occur from the surface to the seafloor are driven by changes in the saltiness and ocean temperature, a process called thermohaline circulation. These currents are carried in a large "global conveyor belt," which includes the AMOC.AMOC stands for Atlantic Meridional Overturning Circulation. The AMOC circulates water from north to south and back in a long cycle within the Atlantic Ocean. This circulation brings warmth to various parts of the globe and also carries nutrients necessary to sustain ocean life. Continue reading &rarr;
- What is longitude? Lines of longitude, also called meridians, are imaginary lines that divide the Earth. They run north to south from pole to pole, but they measure the distance east or west.The prime meridian, which runs through Greenwich, England, has a longitude of 0 degrees. It divides the Earth into the eastern and western hemispheres. The antimeridian is on the opposite side of the Earth, at 180 degrees longitude. Though the antimeridian is the basis for the international date line, actual date and time zone boundaries are dependent on local laws. The international date line zigzags around borders near the antimeridian.Continue reading &rarr;
- What is latitude? Lines of latitude, also called parallels, are imaginary lines that divide the Earth. They run east to west, but measure your distance north or south. The equator is the most well known parallel. At 0 degrees latitude, it equally divides the Earth into the Northern and Southern hemispheres. From the equator, latitude increases as you travel north or south, reaching 90 degrees at each pole.Continue reading &rarr;
- What is a barrier island? Barrier islands form as waves repeatedly deposit sediment parallel to the shoreline. As wind and waves shift according to weather patterns and local geographic features, these islands constantly move, erode, and grow. They can even disappear entirely.They are generally separated from the mainland by tidal creeks, bays, and lagoons. Beaches and sand dune systems form on the side of the island facing the ocean; the side facing the shore often contains marshes, tidal flats, and maritime forests. These areas are important habitat for seabirds, fish and shellfish, and and nesting sea turtles.Continue reading &rarr;
- How long do Greenland sharks live? Scientists have suspected for a while that Greenland sharks lived extremely long lives, but they didn’t have a way to determine how long. The age of other shark species can be estimated by counting growth bands on fin spines or on the shark’s vertebrae, much like rings on a tree. Greenland sharks, however, have no fin spines and no hard tissues in their bodies. Their vertebrae are too soft to form the growth bands seen in other sharks. Scientists could only guess that the sharks lived a long time based on what they knew — the sharks grow at a very slow rate (less than 1 cm per year) and they can reach over 6 meters in size.Continue reading &rarr;
- How much oxygen comes from the ocean? Scientists estimate that 50-80% of the oxygen production on Earth comes from the ocean. The majority of this production is from oceanic plankton — drifting plants, algae, and some bacteria that can photosynthesize. One particular species, Prochlorococcus, is the smallest photosynthetic organism on Earth. But this little bacteria produces up to 20% of the oxygen in our entire biosphere. That’s a higher percentage than all of the tropical rainforests on land combined.Continue reading &rarr;
- What are plankton? The word “plankton” comes from the Greek for “drifter” or “wanderer.” An organism is considered plankton if it is carried by tides and currents, and cannot swim well enough to move against these forces. Some plankton drift this way for their entire life cycle. Others are only classified as plankton when they are young, but they eventually grow large enough to swim against the currents. Plankton are usually microscopic, often less than one inch in length, but they also include larger species like some crustaceans and jellyfish.Continue reading &rarr;
- Can we clean up, stop, or end harmful algal blooms? Harmful algal blooms — often referred to as HABs for short — occur when algae produce toxic or harmful effects on people, fish, shellfish, marine mammals, birds, or other aquatic organisms. Blooms occur in marine and freshwater environments throughout the world, with damaging ecological, social, and economic effects. So why can’t we clean up the algae and take care of this problem? Unfortunately, the answer is not so simple. Harmful algal blooms are a natural process. There are records of HABs from early European colonists arriving to Florida in the 1500s. However, research points to an increase in the frequency and intensity of algal blooms in modern times due to environmental changes caused by humans.Continue reading &rarr;
- What are coquina and tabby? Did you know that near St. Augustine, Florida — the nation’s oldest city — there exists an actual “castle” made of sand? Located on 20.5 acres on the western shore of Matanzas Bay, the Castillo de San Marcos National Monument is the oldest (circa 1695) and largest masonry fort in the continental United States.The Castillo’s masonry, or stonework, is largely comprised of coquina (Spanish for “small shells”) — a natural concrete derived from the ocean. Coquina is a rare form of limestone composed of the shell fragments of ancient mollusks and other marine invertebrates, which, over time, are glued together by dissolved calcium carbonate in the shells. Coquina is also the name of a common tiny clam found everywhere on Florida beaches. Their shells, which come in countless colors, are reflected in the Castillo’s muted hues.A related building material is tabby, often called coastal concrete, which is basically manmade coquina. Tabby is composed of the lime from burned oyster shells mixed with sand, water, ash, and other shells. As far back as the 1600s, Spanish and English settlers used tabby to build their homes and other structures, and to pave their roads, throughout the coastal Carolinas, Georgia, and Florida.Continue reading &rarr;
- What is the carbon cycle? Carbon is the foundation of all life on Earth, required to form complex molecules like proteins and DNA. This element is also found in our atmosphere in the form of carbon dioxide (CO2). Carbon helps to regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of the energy to fuel our global economy.The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change. Where the carbon is located — in the atmosphere or on Earth — is constantly in flux.Watch our animated video about the carbon cycle to get what you need to know in under two minutes.Continue reading &rarr;
- What is a sponge? Sponges are animals with dense skeletons that are highly adapted to their environments, although it is easy to see why they may be mistaken for plants. Sponges are found in a wide variety of colors, shapes, and sizes – and scientists believe that the colors of the sponge may act as a protection from the sun’s harmful UV rays. Most sponges are found in the ocean, but there are certain sponge species that can be found in freshwater environments, as well.Continue reading &rarr;
- What is a tide pool? An archipelago is an area that contains a chain or group of islands scattered in lakes, rivers, or the ocean.              Formed in depressions along the shoreline of rocky coasts, tide pools are filled with seawater that gets trapped as the tide recedes. While these small basins at the ocean’s edge typically range from mere inches to a few feet deep and a few feet across, they are packed with sturdy sea life such as snails, barnacles, mussels, anemones, urchins, sea stars, crustaceans, seaweed, and small fish.Continue reading &rarr;
- What is an archipelago? An archipelago is an area that contains a chain or group of islands scattered in lakes, rivers, or the ocean.              The word “archipelago” comes from the medieval Italian word archi, meaning chief or principal, and the Greek word pelagus, meaning gulf, pool, or pond.Most archipelagos are formed when volcanoes erupt from the ocean floor; these are called oceanic islands. The islands of the Hawaiian archipelago, for example, were formed by a series of volcanic eruptions that began more than 80 million years ago and are still active today.Continue reading &rarr;
- What is the intertidal zone? Intertidal zones exist anywhere the ocean meets the land, from steep, rocky ledges to long, sloping sandy beaches and mudflats that can extend for hundreds of meters. Four physical divisions, each with distinct characteristics and ecological differences, divide the intertidal zone. Continue reading &rarr;
- What is the most common form of ocean litter? Broken bottles, discarded love letters, castoff clothing, candy wrappers, flotsam and jetsam washed ashore: During a walk along a beach, one finds any of these items and more. In all that litter, there is one item more common than any other: cigarette butts.Continue reading &rarr;
- What causes seasickness? Seasickness is a result of a conflict in the inner ear, where the human balance mechanism resides, and is caused by a vessel’s erratic motion on the water. Inside the cabin of a rocking boat, for example, the inner ear detects changes in both up-and-down and side-to-side acceleration as one’s body bobs along with the boat. But, since the cabin moves with the passenger, one’s eyes register a relatively stable scene. Agitated by this perceptual incongruity, the brain responds with a cascade of stress-related hormones that can ultimately lead to nausea, vomiting, and vertigo.Continue reading &rarr;
- What is a heat dome? Summertime means hot weather — sometimes dangerously hot — and extreme heat waves have become more frequent in recent decades. Sometimes, the scorching heat is ensnared in what is called a heat dome. This happens when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets trapped under the high-pressure "dome." Continue reading &rarr;
- Do we still need lighthouses? Though numerous lighthouses still serve seafarers, modern electronic aids to navigation play a larger role in maritime safety in the 21st century.Continue reading &rarr;
- What is a canal? A canal is a manmade waterway that allows boats and ships to pass from one body of water to another. Canals are also used to transport water for irrigation and other human uses. While the advent of more efficient forms of transportation has reduced the need for canals, they still play a vital role as conduits for transportation and foster global commerce.There are two types of canals: waterways and aqueducts. Waterways are the navigable parts of a body of water, and can be located within a bay or open sea, can connect two or more waterbodies, or may even form networks within a city. Aqueducts are used exclusively to transport water for drinking, agriculture, and hydroelectric power.Continue reading &rarr;
- What do windward and leeward mean? An island’s windward side faces the prevailing, or trade, winds, whereas the island’s leeward side faces away from the wind, sheltered from prevailing winds by hills and mountains. As trade winds blow across the ocean, they pick up moist air from the water.Once the damp air makes landfall on an island, it ascends hills and mountains to form condensation, clouds, and precipitation. As the air moves to the other side of the island, it warms up and dries out. Thus, an island’s windward side is wetter and more verdant than its drier leeward side. Meteorologists call this contrast the orographic effect.As an example, the Hawaiian Islands have damp windward sides and drier leeward sides most of the time as a result of the Pacific Ocean’s northeasterly trade winds. Windward locations are generally lush and green. Famously sunny beaches like Oahu’s Waikiki and Maui’s Wailea are found on the islands’ more sheltered leeward sides.Continue reading &rarr;
- How many high tides are there per day? While some places have one high tide and one low tide per day, most coastal locations have two high tides and two low tides a day. These highs and lows typically aren't equal. This is why, in most places, using the phrase "high tide" might be unclear. There's actually high tide and higher high tide (and low and lower low tide).If the Earth were a perfect sphere without large continents, every place would get two equal high and low tides every day. However, the presence of the continents, regional geography and features on the seafloor, among other factors, make tidal patterns more complex.Around the world, there are three basic tidal patterns: semidiurnal, mixed, and diurnal. When both high tides are about equal to each other, and the low tides are also roughly equal, the pattern is called a semidiurnal tide. If the two highs and lows differ substantially, the pattern is called a mixed tide. Where there's only one high and one low tide a day, it's called a diurnal tide. One location can experience different tide patterns throughout the month.Continue reading &rarr;
- What is a SOFAR? How does SOFAR work? Think of the ocean as consisting of various zones, or layers — sort of like oil and vinegar salad dressing before it’s shaken up—except that ocean layers occur due to differences in salinity (salt content) and temperature variations. Saltier water, and colder water, lie beneath less salty, warmer water.  Because of SOFAR, sound emitted at a certain depth bounces between these various layers and can travel for hundreds of miles. This up-and-down bending of low-frequency soundwaves allows soundwaves to travel great distances without the signal losing significant energy. By placing hydrophones at the axis of the sound channel, researchers can record sounds such as whale calls, earthquakes, and manmade noise occurring vast distances from the hydrophones. In some instances, low-frequency sounds can be heard across entire ocean basins! Continue reading &rarr;
- What is a lagoon? Lagoons are separated from larger bodies of water by sandbars, barrier reefs, coral reefs, or other natural barriers. The word "lagoon" derives from the Italian word laguna, which means "pond" or "lake."Although lagoons are well defined geographically, the word “lagoon” is sometimes used as a name for a larger region that contains one or more lagoons. For example, Laguna Madre on the Texas Gulf Coast is actually made up of smaller bays and lagoons, while Laguna Beach in Southern California is actually a beach and not a lagoon at all.There are two types of lagoons: atoll and coastal. Atoll lagoons form when an island completely subsides beneath the water, leaving a ring of coral that continues to grow upwards. At the center of the ring is a body of water that is often deep. The combination of coral growth and water creates a lagoon. It may take as long as 300,000 years for an atoll formation to occur.Continue reading &rarr;
- How do hurricanes affect sea life? When a storm churns across the ocean, the warm surface waters provide additional moisture and can fuel the storm into a hurricane. As the hurricane grows larger and more potent, it can generate waves as high as 60 feet, tossing and mixing warmer surface waters with the colder, saltier water below. The resulting currents can extend as far as 300 feet/91.5 meters below the surface, wreaking deadly havoc on marine life.If the wild currents fail to break up coral reefs in their path, the rain-infused water they bring reduces salt levels and otherwise stresses corals. As the hurricane moves toward shore, the underwater tumult can cause shifting sands and muddy shallow waters, blocking the essential sunlight on which corals and other sea creatures rely.Slow-moving fish and turtles and shellfish beds are often decimated by the rough undercurrents and rapid changes in water temperature and salinity wrought by a hurricane. Sharks, whales, and other large animals swiftly move to calmer waters, however, and, generally speaking, are not overly affected by hurricanes.Continue reading &rarr;
- What is a glass sponge? Glass sponges in the class Hexactinellida are animals commonly found in the deep ocean. Their tissues contain glass-like structural particles, called spicules, that are made of silica (hence their name). Some species of glass sponges produce extremely large spicules that fuse together in beautiful patterns to form a “glass house”—a complex skeleton that often remains intact even after the sponge itself dies. The skeleton of the glass sponge, together with various chemicals, provides defense against many predators. Nonetheless, some starfish are known to feed on these rare creatures of the deep.Continue reading &rarr;
- What is the Bloop? "The Bloop" is the given name of a mysterious underwater sound recorded in the 90s. Years later, NOAA scientists discovered that this sound emanated from an iceberg cracking and breaking away from an Antarctic glacier.Continue reading &rarr;
- How do hurricanes form? Hurricanes are powerhouse weather events that suck heat from tropical waters to fuel their fury. These violent storms form over the ocean, often beginning as a tropical wave—a low pressure area that moves through the moisture-rich tropics, possibly enhancing shower and thunderstorm activity.Continue reading &rarr;
- What is a hydrophone? Just as a microphone collects sound in the air, a hydrophone detects acoustic signals under the water. Most hydrophones are based on a special property of certain ceramics that produces a small electrical current when subjected to changes in underwater pressure. When submerged in the ocean, a ceramic hydrophone produces small-voltage signals over a wide range of frequencies as it is exposed to underwater sounds emanating from any direction.Continue reading &rarr;
- What is ecoforecasting? Ecoforecasts detail how interactions between organisms and their environment may affect ecological phenomena such as animal extinction, the spread of invasive plants and disease, and the health of waterbodies.Continue reading &rarr;
- What is a gyre? Wind, tides, and differences in temperature and salinity drive ocean currents. The ocean churns up different types of currents, such as eddies, whirlpools, or deep ocean currents. Larger, sustained currents—the Gulf Stream, for example—go by proper names. Taken together, these larger and more permanent currents make up the systems of currents known as gyres.There are five major gyres: the North and South Pacific Subtropical Gyres, the North and South Atlantic Subtropical Gyres, and the Indian Ocean Subtropical Gyre.In some instances, the term “gyre” is used to refer to the collections of plastic waste and other debris found in higher concentrations in certain parts of the ocean. While this use of "gyre" is increasingly common, the term traditionally refers simply to large, rotating ocean currents.Continue reading &rarr;
- How Many Species Live in the Ocean? Given the vast size of the ocean, it is impossible to know the exact number of species that live there. Research suggests, however, that the number of species in the ocean is decreasing. The continued decline in the health of many ecosystems, coupled with rising extinction rates, are likely outpacing species’ ability to evolve to tolerate the conditions of our rapidly changing planet. It is not all bad news, though. Researchers around the world continue to study marine life and habitats to help develop new strategies to preserve vital ocean ecosystems.Continue reading &rarr;
- Are tides higher when the moon is directly overhead? Tides originate in the ocean and progress toward the coastlines, where they appear as the regular rise and fall of the sea surface. Thanks to Sir Isaac Newton’s 1687 discovery, we know that tides are very long-period waves that move through the ocean in response to forces exerted by the moon and sun. However, these gravitational forces do not control when high or low tide events occur. Other forces, more regional than the moon or sun, control the tides. Many of them have to do with the geography and shape of the Earth.The shape of our planet has a lot to do with differences in gravitational pull at various locations. If Earth was a true sphere covered by an ocean of constant depth, then it would be true that a high tide event would occur at the location with the moon overhead. The tidal "bulge" would move around the Earth with the moon, but this is not the case with our planet. The Earth is not a true sphere, but bulges slightly at the Equator. It is also dotted with large land masses (continents). Areas where the Earth’s surface is higher, such as mountains, have a stronger gravitational force than do places where the surface is lower, such as a valley or cavern. At the same time, the depth of the world ocean varies greatly. All of these factors play into the height of the tides.Continue reading &rarr;
- What is a meteotsunami? Meteotsunamis are large waves that scientists are just beginning to better understand. Unlike tsunamis triggered by seismic activity, meteotsunamis are driven by air-pressure disturbances often associated with fast-moving weather events, such as severe thunderstorms, squalls, and other storm fronts. The storm generates a wave that moves towards the shore, and is amplified by a shallow continental shelf and inlet, bay, or other coastal feature.Meteotsunamis have been observed to reach heights of 6 feet or more. They occur in many places around the world, including the Great Lakes, Gulf of Mexico, Atlantic Coast, and the Mediterranean and Adriatic Seas. Continue reading &rarr;
- What is a watershed? The size of a watershed (also called a drainage basin or catchment) is defined on several scales—referred to as its Hydrologic Unit Codes (HUC)—based on the geography that is most relevant to its specific area. A watershed can be small, such as a modest inland lake or a single county.Conversely, some watersheds encompass thousands of square miles and may contain streams, rivers, lakes, reservoirs, and underlying groundwater that are hundreds of miles inland. The largest watershed in the United States is the Mississippi River Watershed, which drains 2,981,076 square kilometers from all or parts of 31 U.S. states and two Canadian provinces stretching from the Rockies to the Appalachians!Continue reading &rarr;
- What is a current survey? NOAA's Center for Operational Oceanographic Products and Services provides tidal current predictions to commercial and recreational mariners who rely on this information for safe navigation.  In order to provide the most accurate predictions possible, NOAA must periodically resurvey various coastal and estuarine locations.  Survey locations are selected based on mariners' navigation needs, oceanographic analyses, and the amount of time that has passed since the last survey. Given modern improvements in measurement and computing technology, these surveys greatly improve the accuracy of tidal predictions. In 2017, for example, NOAA concluded a three-year current survey of Puget Sound, Washington, to update the region's tidal current predictions. Prior to the survey, predictions were based on limited amounts of data collected in the 1930s-1960s.Continue reading &rarr;
- What is a backscatter? Backscatter is the reflection of a signal (such as sound waves or light) back in the direction from where it originated. Backscatter is commonly used in medical ultrasounds to understand characteristics of the human body, but in the world of hydrography and marine science, backscatter from soundwaves helps us understand characteristics of the seafloor.Continue reading &rarr;
- What is a ghost forest? As sea level rises, more and more saltwater encroaches on the land. Along the world’s coasts and estuaries, invading seawater advances and overtakes the fresh water that deciduous trees rely upon for sustenance. The salty water slowly poisons living trees, leaving a haunted ghost forest of dead and dying timber. Still standing in or near brackish water, the decaying trees of a ghost forest resemble giant graying pillars that protrude into the air.Continue reading &rarr;
- Where is Earth’s Largest Waterfall? Rivers flowing over Earth’s gorges create waterfalls that are natural wonders, drawing millions of visitors to their breathtaking beauty, grandeur, and power. But no waterfall is larger or more powerful than those that lie beneath the ocean, cascading over immense cataracts hidden from our view.Continue reading &rarr;
- What is eutrophication? Eutrophication is a big word that describes a big problem in the nation's estuaries. Harmful algal blooms, dead zones, and fish kills are the results of a process called eutrophication—which begins with the increased load of nutrients to estuaries and coastal waters.Continue reading &rarr;
- What is high tide flooding? High tide flooding—flooding that leads to public inconveniences such as road closures—is increasingly common as coastal sea levels rise.Continue reading &rarr;
- How does sand form? Sand is the end product of many things, including decomposed rocks, organic by-products, and even parrotfish poop.Continue reading &rarr;
- What does the ocean have to do with human health? Our ocean and coasts affect us all—even those of us who don't live near the shoreline. Consider the economy. Through the fishing and boating industry, tourism and recreation, and ocean transport, one in six U.S. jobs is marine-related. Coastal and marine waters support over 28 million jobs. U.S. consumers spend over $55 billion annually for fishery products. Then there's travel and tourism. Our beaches are a top destination, attracting about 90 million people a year. Our coastal areas generate 85 percent of all U.S. tourism revenues. And let's not forget about the Great Lakes—these vast bodies of water supply more than 40 million people with drinking water. Our ocean, coasts, and Great Lakes serve other critical needs, too—needs that are harder to measure, but no less important—such as climate regulation, nutrient recycling, and maritime heritage. Last but not least, a healthy ocean and coasts provide us with resources we rely on every day, ranging from food, to medicines, to compounds that make our peanut butter easier to spread! So what does all of this have to do with human health?Continue reading &rarr;
- What is a Rossby wave? Oceanic and atmospheric Rossby waves — also known as planetary waves — naturally occur largely due to the Earth's rotation. These waves affect the planet's weather and climate. Waves in the ocean come in many different shapes and sizes. Slow-moving oceanic Rossby waves are are fundamentally different from ocean surface waves. Unlike waves that break along the shore, Rossby waves are huge, undulating movements of the ocean that stretch horizontally across the planet for hundreds of kilometers in a westward direction. They are so large and massive that they can change Earth's climate conditions. Along with rising sea levels, King Tides, and the effects of El Niño, oceanic Rossby waves contribute to high tides and coastal flooding in some regions of the world. About this image: Rossby waves naturally occur in rotating fluids. Within the Earth's ocean and atmosphere, these planetary waves play a significant role in shaping weather. This animation from NASA's Goddard Space Flight Center shows both long and short atmospheric waves as indicated by the jet stream. The colors represent the speed of the wind ranging from slowest (light blue colors) to fastest (dark red). Continue reading &rarr;
- Why should we care about the ocean? The world ocean provides so many benefits. Here are ten things the ocean does for humans and the planet:- The air we breathe: The ocean produces over half of the world's oxygen and absorbs 50 times more carbon dioxide than our atmosphere.- Climate regulation: Covering 70 percent of the Earth's surface, the ocean transports heat from the equator to the poles, regulating our climate and weather patterns.- Transportation: Seventy-six percent of all U.S. trade involves some form of marine transportation.- Recreation: From fishing to boating to kayaking and whale watching, the ocean provides us with many unique activities.- Economic benefits: The U.S. ocean economy produces $282 billion in goods and services and ocean-dependant businesses employ almost three million people.- Food: The ocean provides more than just seafood; ingredients from the sea are found in suprising foods such as peanut butter and soymilk.- Medicine: Many medicinal products come from the ocean, including ingredients that help fight cancer, athritis, Alzheimer's disease, and heart disease.Continue reading &rarr;
- What are the Totten Beacons? In 1513, Spanish explorer Ponce de León sailed into the strong currents of the Florida Straits. Little did he know that within a few years, these uncharted waters, which fed into the Gulf Stream, would become a major international shipping route to and from Europe and the New World.As Europeans explored and colonized the Americas, they took advantage of the Florida Straits' winds and currents. The winds changed direction often, however, easily pounding countless vessels against miles of treacherous submerged coral reefs off the southern Florida coast.By 1852, Lieutenant James B. Totten, the U.S. Army's assistant to the Coast Survey, had installed 15 wooden signal poles in the reefs to create more accurate charts of the Florida Keys. Local mariners quickly recognized that the poles themselves helped them safely navigate the reefs, and by 1855, Totten and his team installed a second generation of 16 poles using a more permanent material—iron. The "beacons" each displayed a letter, starting with "A" and ending with "P." Today, remnants of Totten Beacons are protected as historical resources by the Florida Keys National Marine Sanctuary (FKNMS).Continue reading &rarr;
- What is a tide gauge? A tide gauge, which is one component of a modern water level monitoring station, is fitted with sensors that continuously record the height of the surrounding water level. This data is critical for many coastal activities, including safe navigation, sound engineering, and habitat restoration and preservation.Continue reading &rarr;
- What are brain corals? The cerebral-looking organisms known as brain corals do not have brains, but they can grow six feet tall and live for up to 900 years! Found in the Caribbean, Atlantic, and Pacific Oceans, brain corals display what is known as Meandroid tissue integration. This means that the polyps, which are the basic living unit of corals, are highly associated to one another. Their tissues are more closely connected than those of other corals and are not separated by skeletal structures. Many researchers think that the more integrated a coral's polyp tissue is, the more advanced the coral species.Continue reading &rarr;
- What is a catcher beach? Not to be confused with a dumping ground or heavily trashed public beach, a catcher beach typically receives its accumulations of debris due to its shape and location in combination with high-energy waves, storms, or winds. Awareness and common knowledge of these types of areas vary significantly by state, although many states have a good understanding of where catcher beaches are located. In many cases, catcher beaches are found in remote areas that are difficult to access and can be challenging in terms of debris cleanup and removal.Continue reading &rarr;
- What is a King Tide? A King Tide is a non-scientific term people often use to describe exceptionally high tides. Tides are long-period waves that roll around the planet as the ocean is "pulled" back and forth by the gravitational pull of the moon and the sun as these bodies interact with the Earth in their monthly and yearly orbits. Higher than normal tides typically occur during a new or full moon and when the Earth is at its perigee, or during specific seasons around the countryContinue reading &rarr;
- Where do I get real-time and forecast coastal conditions? NOAA's nowCOAST is a GIS-based webmap service that provides frequently updated ocean observations along with coastal and marine weather forecasts 24 hours a day. The free online map offers point-and-click access to 60 NOAA data products and services all in one place. With nowCOAST, you can get a one-stop-shop look at coastal conditions — real-time and forecast — before you do or plan anything on the water.Continue reading &rarr;
- What is the fastest fish in the ocean? Clocked at speeds in excess of 68 mph, some experts consider the sailfish the fastest fish in the world ocean. Easily recognized, sailfish are named for the spectacular sail-like dorsal fin that extends for nearly the entire length of their silver-blue body. Additionally, the sailfish's upper jaw is far longer than its lower jaw, forming a distinctive bill that looks like—and sometimes acts like—a spear.Continue reading &rarr;
- How does sea ice affect global climate? Sea ice is frozen water that forms, expands, and melts in the ocean. It is different from icebergs, glaciers, ice sheets, and ice shelves, which originate on land. For the most part, sea ice expands during winter months and melts during summer months, but in certain regions, some sea ice remains year-round. About 15 percent of the world's oceans are covered by sea ice during part of the year.While sea ice exists primarily in the polar regions, it influences the global climate. The bright surface of sea ice reflects a lot of sunlight out into the atmosphere and, importantly, back into space. Because this solar energy "bounces back" and is not absorbed into the ocean, temperatures nearer the poles remain cool relative to the equator.Continue reading &rarr;
- What causes a sea turtle to be born male or female? In most species, gender is determined during fertilization. However, the sex of most turtles, alligators, and crocodiles is determined after fertilization. The temperature of the developing eggs is what decides whether the offspring will be male or female. This is called temperature-dependent sex determination, or TSD.Continue reading &rarr;
- What are the oldest living animals in the world? Scientists now believe that some corals can live for up to 5,000 years, making them the longest living animals on Earth.Continue reading &rarr;
- What are the Roaring Forties? During the Age of Sail (circa 15th  to 19th centuries), these strong prevailing winds propelled ships across the Pacific, often at breakneck speed. Nevertheless, sailing west into heavy seas and strong headwinds could take weeks, especially around Cape Horn at the southern tip of South America, making it one of the most treacherous sailing passages in the world. The Roaring Forties take shape as warm air near the equator rises and moves toward the poles. Warm air moving poleward (on both sides of the equator) is the result of nature trying to reduce the temperature difference between the equator and at the poles created by uneven heating from the sun.Continue reading &rarr;
- Are all fish cold-blooded? Not all fish are cold-blooded. In 2015, researchers with the NOAA Southwest Fisheries Science Center revealed the opah, or moonfish, as the first fully warm-blooded fish.  Although not as warm as mammals and birds, the opah circulates heated blood throughout its body, giving it a competitive advantage in the cold ocean depths from 150 to 1,300 feet below the surface.Continue reading &rarr;
- What is the Pineapple Express? Atmospheric rivers are narrow regions in the atmosphere that transport much of the moisture from the tropics to northern latitudes. Atmospheric rivers are part of the Earth's ocean water cycle, and are tied closely to both water supply and flood risks.A well-known example of a strong atmospheric river is called the "Pineapple Express" because moisture builds up in the tropical Pacific around Hawaii and can wallop the U.S. West Coast with heavy rainfall.Continue reading &rarr;
- Where do fish go when it freezes outside? Have you ever wondered how fish survive in cold winter weather, or where they go when lakes and ponds freeze over? Like many people, fish tend to be less active in the cold. As cold-blooded creatures, their metabolism dips when temperatures take a dive.The layer of ice that forms on top of a lake, pond, river, or stream provides some insulation that helps the waterbody retain its heat. Because warm water sinks, freshwater fish often gather in groups near the bottom. Some species, like koi and gobies, may burrow into soft sediments and go dormant like frogs and other amphibians, but most fish simply school in the deepest pools and take a "winter rest."In this resting state, fishes' hearts slow down, their needs for food and oxygen decrease, and they move about very little. If you've ever gone ice fishing, you know that a long line, a slow, colorful lure, and a hearty portion of patience are often required to land this quiet quarry! Popular ice-fishing species include walleye, northern pike, yellow perch, and rainbow trout.Continue reading &rarr;
- What is ocean noise? Ocean noise refers to sounds made by human activities that can interfere with or obscure the ability of marine animals to hear natural sounds in the ocean. Many marine organisms rely on their ability to hear for their survival. Sound is the most efficient means of communication underwater and is the primary way that many marine species gather and understand information about their environment. Many aquatic animals use sound to find prey, locate mates and offspring, avoid predators, guide their navigation and locate habitat, and listen and communicate with each other.Continue reading &rarr;
- What are the trade winds? Known to sailors around the world, the trade winds and associated ocean currents helped early sailing ships from European and African ports make their journeys to the Americas. Likewise, the trade winds also drive sailing vessels from the Americas toward Asia. Even now, commercial ships use "the trades" and the currents the winds produce to hasten their oceanic voyages. Continue reading &rarr;
- How are satellites used to observe the ocean? Satellites are amazing tools for observing the Earth and the big blue ocean that covers more than 70 percent of our planet. By remotely sensing from their orbits high above the Earth, satellites provide us much more information than would be possible to obtain solely from the surface.Using satellites, NOAA researchers closely study the ocean. Information gathered by satellites can tell us about ocean bathymetry, sea surface temperature, ocean color, coral reefs, and sea and lake ice. Scientists also use data collection systems on satellites to relay signals from transmitters on the ground to researchers in the field—used in applications such as measuring tidal heights and the migration of whales. Transmitters on satellites also relay position information from emergency beacons to help save lives when people are in distress on boats, airplanes, or in remote areas. Continue reading &rarr;
- What is a sea lamprey? Among the most primitive of all vertebrate species, the sea lamprey is a parasitic fish native to the northern and western Atlantic Ocean. Due to their similar body shapes, lampreys have sometimes inaccurately been called "lamprey eels," but they are actually more closely related to sharks!Unlike "bony" fishes like trout, cod, and herring, lampreys lack scales, fins, and gill covers. Like sharks, their skeletons are made of cartilage. They breathe through a distinctive row of seven pairs of tiny gill openings located behind their mouths and eyes.But the anatomical trait that makes the sea lamprey an efficient killer of lake trout and other bony fishes is its disc-shaped, suction-cup mouth, ringed with sharp, horny teeth, with which it latches on to an unfortunate fish. The lamprey then uses its rough tongue to rasp away the fish's flesh so it can feed on its host's blood and body fluids. One lamprey kills about 40 pounds of fish every year.Continue reading &rarr;
- What is an oil seep? Did you know that naturally occurring oil seeps from the seafloor are the largest source of oil entering the world ocean? In fact, they account for nearly half of the oil released into the ocean environment every year. Seeps occur when crude oil leaks from fractures in the seafloor or rises up through seafloor sediments, in much the same way that a freshwater spring brings water to the surface. The waters off of Southern California are home to hundreds of naturally occurring oil and natural gas seeps. Continue reading &rarr;
- What is coral spawning? Once a year, on cues from the lunar cycle and the water temperature, entire colonies of coral reefs simultaneously release their tiny eggs and sperm, called gametes, into the ocean. The phenomenon brings to mind an underwater blizzard with billions of colorful flakes cascading in white, yellow, red, and orange.Continue reading &rarr;
- Why do scientists measure sea surface temperature? Sea surface temperature provides fundamental information on the global climate system. Because the ocean covers 71 percent of Earth's surface, scientists record sea surface temperature (SST) to understand how the ocean communicates with Earth's atmosphere. SST provides fundamental information on the global climate system. SST is an essential parameter in weather prediction and atmospheric model simulations, and is also important for the study of marine ecosystems.Continue reading &rarr;
- What is the difference between local sea level and global sea level? Global sea level trends and relative sea level trends are different measurements. Just as the surface of the Earth is not flat, the surface of the ocean is also not flat — in other words, the sea surface is not changing at the same rate at all points around the globe. Sea level rise at specific locations may be more or less than the global average due to many local factors: subsidence, ocean currents, variations in land height, and whether the land is still rebounding from the compressive weight of Ice Age glaciers.Continue reading &rarr;
- What is marine telemetry? Marine telemetry interprets into data the movements and behavior of animals as they move through oceans, coastal rivers, estuaries, and the Great Lakes.  Telemetry devices, called tags, are affixed to a wide range of marine species, from tiny salmon smolts to giant 150-ton whales. Tags are attached to the outside of an animal with clips, straps, or glue, and are sometimes surgically inserted in an animal's body.Continue reading &rarr;
- What are the doldrums? Known to sailors around the world as the doldrums, the Inter-Tropical Convergence Zone, (ITCZ, pronounced and sometimes referred to as the “itch”), is a belt around the Earth extending approximately five degrees north and south of the equator. Here, the prevailing trade winds of the northern hemisphere blow to the southwest and collide with the southern hemisphere’s driving northeast trade winds.Continue reading &rarr;
- What are beach advisories and beach closures? A beach advisory leaves it up to users as to whether they wish to risk going into the water. In the case of a beach closure, the state and/or local government decides that water conditions are unsafe for swimmers and other users.How can beach-goers avoid the disappointment of arriving at their summer vacation destination only to find that authorities advise them not to swim there or that the beaches are closed altogether?Unfortunately, there is no central database that provides information on beach closures and advisories in real time. The best way to find information on the current water quality of a particular beach is to plan ahead.Continue reading &rarr;
- What are microplastics? Plastic is the most prevalent type of marine debris found in our ocean and Great Lakes. Plastic debris can come in all shapes and sizes, but those that are less than five millimeters in length (or about the size of a sesame seed) are called “microplastics.”As an emerging field of study, not a lot is known about microplastics and their impacts yet. The NOAA Marine Debris Program is leading efforts within NOAA to research this topic. Standardized field methods for collecting sediment, sand, and surface-water microplastic samples have been developed and continue to undergo testing. Eventually, field and laboratory protocols will allow for global comparisons of the amount of microplastics released into the environment, which is the first step in determining the final distribution, impacts, and fate of this debris.Continue reading &rarr;
- How does land-based pollution threaten coral reefs? Impacts from land-based sources of pollution—including coastal development, deforestation, agricultural runoff, and oil and chemical spills—can impede coral growth and reproduction, disrupt overall ecological function, and cause disease and mortality in sensitive species. It is now well accepted that many serious coral reef ecosystem stressors originate from land-based sources, most notably toxicants, sediments, and nutrients.Within the U.S., there are numerous locations where coral reef ecosystems are highly impacted by watershed alteration, runoff, and coastal development. On U.S. islands in the Pacific and Caribbean, significant changes in the drainage basins due to agriculture, deforestation, grazing of feral animals, fires, road building, and urbanization have increased the volume of land-based pollution released to adjacent coral reef ecosystems.Many of these issues are made worse because of the geographic and climatic characteristics found in tropical island areas. Together they create unique management challenges.Continue reading &rarr;
- Can a coral reef recover from bleaching and other stressful events? Climate change and ocean acidification can result in mass coral bleaching events, increased susceptibility to disease, slower growth and reproductive rates, and degraded reef structure.There are no quick fixes when it comes to a changing climate. In the long term, coral reefs around the world will benefit the most from the reduction of greenhouse gases. In the short term, we can improve coral reef resilience by addressing local stressors, like runoff from land-based sources of pollution and overharvesting of fish.NOAA’s Coral Reef Conservation Program is helping local managers and communities do just that. The idea is simple. We know climate change is the single greatest global threat to coral reefs. Promoting reef resilience is a local solution. A resilient coral reef is one that can either resist a large-scale stressful event or recover from it. For this to happen, local threats must be kept to a minimum to reduce stress and improve overall reef condition. Scientists are also honing ways to evaluate how resilient a coral reef ecosystem is so that managers can take targeted actions that have the greatest impact.Continue reading &rarr;
- How does overfishing affect coral reefs? Coral reef ecosystems support important commercial, recreational, and subsistence fishery resources in the U.S and its territories. Fishing also plays a central social and cultural role in many island and coastal communities, where it is often a critical source of food and income.The impacts from unsustainable fishing on coral reef areas can lead to the depletion of key reef species in many locations. Such losses often have a ripple effect, not just on the coral reef ecosystems themselves, but also on the local economies that depend on them. Additionally, certain types of fishing gear can inflict serious physical damage to coral reefs, seagrass beds, and other important marine habitats.Coral reef fisheries, though often relatively small in scale, may have disproportionately large impacts on the ecosystem if conducted unsustainably. Rapid human population growth, increased demand, use of more efficient fishery technologies, and inadequate management and enforcement have led to the depletion of key reef species and habitat damage in many locations.Continue reading &rarr;
- How does climate change affect coral reefs? Climate change is the greatest global threat to coral reef ecosystems. Scientific evidence now clearly indicates that the Earth's atmosphere and ocean are warming, and that these changes are primarily due to greenhouse gases derived from human activities.As temperatures rise, mass coral bleaching events and infectious disease outbreaks are becoming more frequent. Additionally, carbon dioxide absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering seawater chemistry through decreases in pH. This process is called ocean acidification.Climate change will affect coral reef ecosystems, through sea level rise, changes to the frequency and intensity of tropical storms, and altered ocean circulation patterns. When combined, all of these impacts dramatically alter ecosystem function, as well as the goods and services coral reef ecosystems provide to people around the globe.Continue reading &rarr;
- How do sea turtles hatch? In summertime when the weather is warm, pregnant female sea turtles return to the beaches where they themselves hatched years before. They swim through the crashing surf and crawl up the beach searching for a nesting spot above the high water mark. Using her back flippers, the reptile digs a nest in the sand. Digging the nest and laying her eggs usually takes from one to three hours, after which the mother turtle slowly drags herself back to the ocean. The sea turtle lays up to 100 eggs, which incubate in the warm sand for about 60 days. The temperature of the sand determines the genders of baby sea turtles, with cooler sand producing more males and warmer sand producing more females. The phenomenon is called Temperature-Dependent Sex Determination, or TSD, and governs the genders of other reptiles, too, including alligators and crocodiles. Current NOAA research suggests that warming trends due to climate change may cause a higher ratio of female sea turtles, potentially affecting genetic diversity.Continue reading &rarr;
- What is ocean etiquette? Wildlife viewing is a popular recreation activity, but it is important to know how to interact with ocean wildlife so that you can make the right decisions. Irresponsible human behavior can disturb animals, destroy important habitats, and even result in injury to animals and people.Continue reading &rarr;
- What is the highest point on Earth as measured from Earth's center? Mount Everest, located in Nepal and Tibet, is usually said to be the highest mountain on Earth. Reaching 29,029 feet at its summit, Everest is indeed the highest point above global mean sea level—the average level for the ocean surface from which elevations are measured. But the summit of Mt. Everest is not the farthest point from Earth’s center.Earth is not a perfect sphere, but is a bit thicker at the Equator due to the centrifugal force created by the planet’s constant rotation. Because of this, the highest point above Earth’s center is the peak of Ecuador’s Mount Chimborazo, located just one degree south of the Equator where Earth’s bulge is greatest. The summit of Chimborazo is 20,564 feet above sea level. However, due to the Earth’s bulge, the summit of Chimborazo is over 6,560 feet farther from the center of the Earth than Everest’s peak. That makes Chimborazo the closest point on Earth to the stars.  Continue reading &rarr;
- What is a living shoreline? Living shorelines are a green infrastructure technique using native vegetation alone or in combination with offshore sills to stabilize the shoreline. Living shorelines provide a natural alternative to ‘hard’ shoreline stabilization methods like stone sills or bulkheads, and provide numerous benefits including nutrient pollution remediation, essential fish habitat provision, and buffering of shoreline from waves and storms. Living shorelines are known to store carbon (known as carbon sequestration), which keeps carbon out of the atmosphere. Continued use of this approach to coastal resilience will result in increased carbon sequestration and storage, potentially mitigating the effects of climate change.Continue reading &rarr;
- What is an oil spill trajectory? During the threat of an oil spill, responders need to know where that spilled oil will go in order to protect shorelines with containment boom, stage cleanup equipment, or close areas for fishing and boating. In order to answer these questions, NOAA oceanographers use specialized computer models to predict the movement of spilled oil on the water surface. They predict where the oil is most likely to go and how soon it may arrive there. During a major spill response, trajectory maps are created to show predictions for the path of spilled oil.Continue reading &rarr;
- What is a pocosin? Pocosins are generally found along the Atlantic coastal plain of the United States, from southern Virginia to northern Florida. These areas typically occur in broad, low-lying shallow basins that do not drain naturally. Pocosins are formed by the accumulation of organic matter, resembling black muck, which builds up over thousands of years. This accumulation of material causes the soil to be highly acidic and nutrient-deficient.Continue reading &rarr;
- What are barnacles? Of the more than 1,400 species of barnacles found in the world’s waterways, the most common ones are called "acorn barnacles." As anyone who’s ever maintained a vessel knows, removing barnacles requires some elbow grease (or a pressure washer). That's why some boaters call them by their slang name: "crusty foulers."Continue reading &rarr;
- What is GPS? For thousands of years, humans found their way by looking to the sky. Sailors used the constellations, sun, and moon to navigate to distant shores. Today, all that's needed is a device called a GPS receiver. GPS stands for Global Positioning System, and it lets us know where we are and where we are going anywhere on Earth.Continue reading &rarr;
- What is the Great Loop? The Great Loop is a continuous waterway that recreational mariners can travel that includes part of the Atlantic, Gulf Intracoastal Waterways, the Great Lakes, Canadian Heritage Canals, and the inland rivers of America's heartland. Anyone who completes the journey is then named an official 'Looper.'For a safe and enjoyable trip, there are a few things to consider when traveling the Great Loop—a great amount of time, a boat with less than a five foot draft to travel inland waterways, NOAA nautical charts, and a NOAA radio. Along the way, it is possible to visit a number of national marine sanctuaries and estuarine research reserves.Continue reading &rarr;
- What color is an iceberg? Most people would say that icebergs are white—and most of them are. But did you know that icebergs can also appear in spectacular shades of blue and green? An iceberg looks white because compressed snow on its surface contains large numbers of tiny air bubbles and crystal edges that equally reflect all wavelengths of visible light.As more and more heavy snow accumulates atop an iceberg, the air bubbles get compressed, forcing the smaller ice crystals to grow together and merge into larger grains. When the iceberg is underwater, the air bubbles are squeezed out and washed away. Then, when light encounters the dense, compressed ice, much of the light penetrates it. The ice absorbs longer wavelengths of colors, such as red and yellow. Colors of shorter wavelengths, like green and blue, reflect the light. This "leftover" blue-green light is what gives some icebergs their remarkable colors.Additionally, algae often grow on the underwater sides of icebergs, producing beautiful green stripes in the ice. These are readily seen when an iceberg rolls over and sections that were previously underwater are exposed.Continue reading &rarr;
- What is marine biogeography? Marine biogeography is the study of marine species, the geographic distribution of their habitats, and the relationships between living organisms and the environment. By mapping benthic habitats, studying what occurs on the bottom of a body of water, and assessing the relationships between the environment and the organisms that live there, biogeographers provide useful information to protect and conserve marine resources.Marine biogeographers often use Geographic Information Systems, or GIS, to aid in their research of marine animals, plants, and habitats. Scientists and GIS specialists develop map-based data that describe the distribution and ecology of living marine resources and their connections to human communities. State and federal planners can apply these tools and information to position aquaculture sites and alternative energy facilities, and to protect fisheries and coral spawning areas. Information from biogeographers allows planners to consider possible scenarios, such as new development, that may, or may not, impact the environment.Continue reading &rarr;
- What is the Forchhammer's Principle? In 1865, the Danish geologist and mineralogist Johan Georg Forchhammer, with the help of naval and civilian collaborators, collected numerous samples of seawater from the Northern Atlantic and the Arctic Ocean. He wanted to determine why the salinity (or "saltiness") of seawater varies in different areas of the ocean.Forchhammer put the samples through a detailed series of chemical analyses and found that the proportions of the major salts in seawater stay about the same everywhere. This constant ratio is known as Forchhammer's Principle, or the Principle of Constant Proportions. In addition to this principal, Forchhammer is credited with defining the term salinity to mean the concentration of major salts in seawater.Continue reading &rarr;
- What is seaspeak? Whether on the high seas or at port, misunderstood communication can lead to serious and even dangerous situations. "Seaspeak", the official language of the seas, helps to prevent miscommunication.Continue reading &rarr;
- What is GRAV-D? GRAV-D measures and monitors Earth’s gravity field to support the geoid—a model of roughly global mean sea level used to measure precise surface elevations—so that it may serve as the “zero reference surface” for all heights in the nation. Accurate heights are critical to many scientific endeavors, but are particularly important for protecting low-lying coastal ecosystems.Continue reading &rarr;
- What is a NOAA tide table? A tide table provides daily high and low tide predictions. NOAA tide tables are available for more than 3,000 locations around the nation. NOAA’s Center for Operational Oceanographic Products and Services and predecessor agencies have produced tide tables for more than 150 years.Continue reading &rarr;
- What are the vampire squid and the vampire fish? The vampire squid is a small ( 12-inch-long ) cephalopod found in deep temperate and tropical seas. Originally thought to be an octopus because it lacks the two long tentacles that usually extend past a squid’s eight arms, the vampire squid possesses characteristics of both squid and octopi, and occupies its own order in taxonomy (scientific classification).On the freshwater side, the vampire fish is a nickname for the payara, an abundant gamefish found in the Amazon Basin. While this large, 1.5-to-3 feet, fish does not suck the blood of its prey, its six-inch-long fangs, which protrude from an undershot jaw, result in a face only a (payara) mother could love.Continue reading &rarr;
- How does NOAA help clean up oil and chemical spills? Just like we may need sponges, scrub brushes, and a disinfectant to expel a mess in our house or yard, emergency responders employ a variety of tools and techniques to remove oil and chemicals spilled in our rivers, bays, and oceans, and washed up on our shores.For more than 30 years, NOAA's Office of Response and Restoration has played a leading role in the evolving science of hazardous materials (also known as "HAZMAT") spill response. Check out our collection of THREE infographics for a clear explanation of this always complex process.Continue reading &rarr;
- What is a maritime forest? Maritime forests are shoreline estuaries along coastal barrier islands that are relatively pristine and support a great diversity of plants and animals. Maritime forests remain largely untouched by commercial development and closely resemble the woodlands where Native Americans inhabited and early settlers settled hundreds of years ago. Trees, bushes, and other plants in maritime forests and estuaries withstand strong winds, periodic flooding, and salt spray. Many species of mammals and reptiles make the forests their home and thousands of birds migrate to maritime forests each year.Continue reading &rarr;
- What is a High Seas Forecast? NOAA's High Seas Forecasts are weather forecasts and data transmitted around the world in real- and near-real-time.Continue reading &rarr;
- What is a bight? A bight is a long, gradual bend or recess in the shoreline that forms a large, open bay. Bights are shallow and may pose hazards to navigation, so their depths, in addition to any submerged features like sand bars and rock formations, are clearly marked on nautical charts.Continue reading &rarr;
- What is a thermocline? Bodies of water are made up of layers, determined by temperature. The top surface layer is called the epipelagic zone, and is sometimes referred to as the "ocean skin" or "sunlight zone".  This layer also interacts with the wind and waves, which mixes the water and distributes the warmth throughout. At the base of this layer is the thermocline. A thermocline is the transition layer between the warmer mixed water at the surface and the deep cooler water below.  It is relatively easy to tell when you have reached the thermocline in a body of water because there is a sudden change in temperature.  In the thermocline, the temperature decreases rapidly from the mixed layer temperature to the much colder deep water temperature.Continue reading &rarr;
- What is a Portuguese Man o’ War? The Portuguese man o’ war, (Physalia physalis) is often called a jellyfish, but is actually a species of siphonophore, a group of animals that are closely related to jellyfish. A siphonophore is unusual in that it is a comprised of a colony of specialized, genetically identical individuals called zooids — clones — with various forms and functions, all working together as one. Each of the four specialized parts of a man ‘o war is responsible for a specific task, such as floating, capturing prey, feeding, and reproduction. Found mostly in tropical and subtropical seas, men of war are propelled by winds and ocean currents alone, and sometimes float in legions of 1,000 or more! Continue reading &rarr;
- What is subsidence? Land subsidence is a gradual settling or sudden sinking of the Earth’s surface. This geodetic mark in Louisiana is anchored deep below the ground and was level with the ground when it was originally placed there, but now the ground around the mark has subsided.Continue reading &rarr;
- What is a wetland? A wetland is an area of land that is saturated with water.Continue reading &rarr;
- What is HAZMAT? HAZMAT is an abbreviation for "hazardous materials."Continue reading &rarr;
- What is an ocean glider? An ocean glider is an autonomous underwater vehicle used to collect ocean data.Continue reading &rarr;
- What is glacial isostatic adjustment? Glacial isostatic adjustment is the ongoing movement of land once burdened by ice-age glaciers.Continue reading &rarr;
- How does NOAA monitor water levels around the nation? NOAA monitors water levels in the U.S. with the National Water Level Observation Network.Continue reading &rarr;
- How do natural disasters contribute to marine debris? The high winds, heavy rains, storm surge, and flooding associated with natural disasters can pull large structures and other articles into surrounding waters.    Continue reading &rarr;
- What is a marsh organ? The "marsh organ" is a simple instrument that helps scientists study sea-level rise.    Continue reading &rarr;
- What is a nautilus? The nautilus is a mollusk that uses jet propulsion to roam the ocean deep.Continue reading &rarr;
- What is a platypus? The platypus is a remarkable mammal found only in Australia.Continue reading &rarr;
- What is spat? Once oyster larvae permanently attach to a surface, they are known as spat.Continue reading &rarr;
- What is a turbidity current? A turbidity current is a rapid, downhill flow of water caused by increased density due to high amounts of sediment.    Continue reading &rarr;
- What is geocaching? Geocaching is an outdoor treasure-hunting activity that uses GPS-enabled devices.Continue reading &rarr;
- What is a geographic information system? GIS is a computer system that captures, stores, checks, and displays information related to positions on Earth’s surface.Continue reading &rarr;
- What is the Census of Marine Life? The Census of Marine Life was an international project that recorded the diversity, distribution, and abundance of life in the ocean.Continue reading &rarr;
- What is aquaculture? Aquaculture is the breeding, rearing, and harvesting of fish, shellfish, plants, algae and other organisms in all types of water environments.Continue reading &rarr;
- What are Mesophotic Coral Ecosystems? Mesophotic coral ecosystems exist in low light—"meso" means middle and "photic" refers to light.Continue reading &rarr;
- Why does the ocean have waves? Waves are created by energy passing through water, causing it to move in a circular motion.Continue reading &rarr;
- What is an Operational Forecast System? An Operational Forecast System provides a nowcast and forecast of oceanographic conditions.Continue reading &rarr;
- How far does sound travel in the ocean? The distance that sound travels in the ocean varies greatly, depending primarily upon water temperature and pressure.Continue reading &rarr;
- Do fish sleep? While most fish rest by reducing their activity and metabolism, fish "sleep" is different from that of land mammals.Continue reading &rarr;
- What is blue carbon? Blue carbon is a term used to described the carbon captured by the world's ocean and coastal ecosystems.>Continue reading &rarr;
- What is PORTS®? PORTS® stands for Physical Oceanographic Real Time System. NOAA PORTS® is an information system that measures and disseminates the oceanographic and meteorological data that mariners need to navigate safely.Continue reading &rarr;
- What is nuisance flooding? High tide flooding, sometimes referred to as "nuisance" flooding, is flooding that leads to public inconveniences such as road closures. It is increasingly common as coastal sea levels rise.Continue reading &rarr;
- What is tectonic shift? Tectonic shift is the movement of the plates that make up Earth’s crust.Continue reading &rarr;
- What is a whale fall? Dead whales, or whale falls, provide years to decades of nutrients for deepwater creatures.Continue reading &rarr;
- What are the horse latitudes? The horse latitudes are regions of the subtropics characterized by calm winds and little precipitation..Continue reading &rarr;
- Are horseshoe crabs really crabs? Horseshoe crabs are "living fossils" more closely related to spiders and scorpions than they are to crabs. .Continue reading &rarr;
- When Was the First Earth Day? The first Earth Day took place on April 22, 1970.Continue reading &rarr;
- What is a pelagic fish? Pelagic fish inhabit the water column (not near the bottom or the shore) of coasts, open oceans, and lakes.Continue reading &rarr;
- What is bombogenesis? Bombogenesis is a popular term that describes a midlatitude cyclone that rapidly intensifies.                   Continue reading &rarr;
- What do geodesists do? Geodesists measure and monitor the Earth’s size and shape, geodynamic phenomena (e.g., tides and polar motion), and gravity field to determine the exact coordinates of any point on Earth and how that point will move over time.                    Continue reading &rarr;
- What is the International Date Line? " />                The International Date Line serves as the "line of demarcation" between two consecutive calendar dates.Continue reading &rarr;
- What is the longest-lived marine mammal? Scientists agree that the bowhead whale has the longest lifespan of  all marine mammals.Continue reading &rarr;
- What is an anchialine pool? An anchialine pool is an enclosed water body or pond with an underground connection to the ocean.
- What is an artificial reef? An artificial reef is a manmade structure that may mimic some of the characteristics of a  natural reef.
- Are there oceans on other planets? Currently, Earth is the only known planet (or moon) to have consistent, stable bodies of liquid water on its surface. In our solar system, Earth orbits around the sun in an area called the habitable zone. The temperature, along with an ample amount of atmospheric pressure within this zone, allows water to be liquid for long periods of time. There is growing evidence suggesting that the planet Mars has subsurface liquid water, but this is yet to be confirmed. Other than Earth, Europa (one of Jupiter’s fifty known moons) is the only celestial body in our solar system with evidence suggesting there is an ocean.
- What is dredging? Dredging is the removal of material from the bottom of lakes, rivers, harbors, and other water bodies. It is a routine necessity in waterways around the world because sedimentation—the natural process of sand and silt washing downstream—gradually fills channels and harbors.
- What is a slough? A slough (pronounced "slew") is typically used to describe wetlands. Sloughs along the edges of rivers form where the old channel of the river once flowed. These areas are also referred to as oxbows because they tend to form at a bend in the old river bed, making them look like the horns of an ox when viewed from the air.
- Is the Earth round? While the earth appears to be round when viewed from the vantage point of space, it is actually closer to an ellipsoid. However, even an ellipsoid does not adequately describe the earth’s unique and ever-changing shape.
- What is a hurricane? A hurricane is a type of storm called a tropical cyclone, which forms over tropical or subtropical waters.
- Was Moby Dick a real whale? While Moby Dick was not a real whale, real-life events inspired the classic novel.
- Why do we name tropical storms? Until the early 1950s, tropical storms and hurricanes were tracked by year and the order in which they occurred during that year. Over time, it was learned that the use of short, easily remembered names in written as well as spoken communications is quicker and reduces confusion when two or more tropical storms occur at the same time. In the past, confusion and false rumors resulted when storm advisories broadcast from radio stations were mistaken for warnings concerning an entirely different storm located hundreds of miles away.
- What is a seiche? A seiche is a "standing" wave oscillating in a body of water.
- Why do mariners use port and starboard instead of left and right? Unlike left and right, "port" and "starboard" refer to fixed locations on a vessel.
- What is a fish ladder? A fish ladder is a structure that allows migrating fish passage over or around an obstacle on a river.
- What is a bivalve mollusk? Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate.
- What is ocean acidification? Ocean acidification refers to a reduction in the pH of the ocean over an extended period time, caused primarily by uptake of carbon dioxide (CO2) from the atmosphere.
- What are PBDEs? PBDEs, or polybrominated diphenyl ethers, are a class of fire retardant chemicals.
- What is a Plimsoll line? A commercial ship is properly loaded when the ship’s waterline equals the ship’s Plimsoll line.
- What is lidar? Lidar — Light Detection and Ranging — is a remote sensing method used to examine the surface of the Earth.
- What is the most venomous marine animal? The Australian box jellyfish is considered the most venomous marine animal.
- Why do we have spring tides in the fall? A spring tide refers to the  'springing forth' of the tide during new and full moon.
- What is the difference between storm surge and storm tide? Storm surge is the abnormal rise in seawater level during a storm, measured as the height of the water above the predicted astronomical tide. The surge is caused primarily by a storm’s winds pushing water onshore. The amplitude of the storm surge at any given location depends on the orientation of the coast line with the storm track; the intensity, size, and speed of the storm; and the local bathymetry.
- What is the mariner's 1-2-3 rule? The Mariner's 1-2-3 Rule is the guideline mariners follow to keep out of a tropical storm or hurricane's path.
- What is the difference between a hurricane watch and a warning? Hurricane warnings indicate that hurricane conditions (sustained winds of 74 mph or higher) are expected somewhere within the specified area.A hurricane watch means that hurricane conditions (sustained winds of 74 mph or higher) are possible within the specified area.
- What is the difference between an AUV and a ROV? AUV stands for autonomous underwater vehicle and is commonly known as unmanned underwater vehicle. A remotely operated vehicle (ROV) is an unoccupied underwater robot that is connected to a ship by a series of cables.
- What is shoreline armoring? "Armoring" is the practice of using physical structures to protect shorelines from coastal erosion.
- What is the difference between a nautical mile and a knot? A nautical mile is based on the circumference of the Earth, and is equal to one minute of latitude. It is slightly more than a statute (land measured) mile (1 nautical mile = 1.1508 statute miles). Nautical miles are used for charting and navigating.
- What is 'Old Sow'? When the tide comes in from the Bay of Fundy, located off the Atlantic Coast between the State of Maine and the Province of New Brunswick, a tremendous amount of ocean water, called a current, flows swiftly into a confined area called the Western Passage before emptying upriver into Passamaquoddy Bay. After making a sharp right turn to the north and traversing a deep trench, flowing past an underwater mountain, and encountering several countercurrents, a portion of the current "pinches off" to form the huge circular current called Old Sow, and, often, several smaller ones, nicknamed "piglets." Circular currents of all sizes are commonly known as whirlpools, vortexes, eddies, and gyres.
- Are mermaids real? No evidence of mermaids has ever been found.
- Where is Point Nemo? Want to get away from it all? You can't do better than a point in the  Pacific Ocean popularly known as  'Point Nemo,' named after the famous submarine sailor from Jules Verne's Twenty Thousand Leagues Under the Sea.
- What's the difference between a threatened and endangered species? Under the Endangered Species Act (ESA), a species may be listed as either threatened or endangered depending on their risk for extinction.  The ESA defines an endangered species as "any species which is in danger of extinction throughout all or a significant portion of its range." Endangered species are automatically protected by prohibitions of several types of "take," including harming, harassing, collecting, or killing, under Section 9 of the ESA. There are some limited exceptions to these rules listed in Section 10 of the ESA. The Kemp's ridley turtle, considered the smallest marine turtle in the world, is listed as an endangered species throughout its range of the Gulf of Mexico and entire U.S. Atlantic seaboard..
- Why are scientists concerned about Asian tiger shrimp? Research is underway to determine if invasive Asian tiger shrimp  in U.S. Atlantic  waters pose a threat to native species or the environment.  Asian tiger  shrimp are native to Indo-Pacific, Asian, and Australian waters, but are now  found along the southeast and Gulf coasts of the United States. While small numbers of  this invasive species have been reported in U.S. waters for over a decade,  sightings have notably increased over the past few years.
- What is a perigean spring tide? A perigean spring tide occurs when the moon is new or full and closest to Earth.
- What is sea foam? If you scoop up some water from the ocean in a clear glass and look at it closely, you'll see that it's chock full of tiny particles. Sea water contains dissolved salts, proteins, fats, dead algae, and a bunch of other bits and pieces of organic matter. If you shake this glass of ocean water vigorously, small bubbles will form on the surface of the liquid.      Sea foam forms in this way -- but on a much grander scale -- when the ocean is agitated by wind and waves. Each coastal region has differing conditions governing the formation of sea foams.
- How big is the Atlantic Ocean? The Atlantic Ocean covers an area of approximately 41,105,000 square miles (106,460,000 square kilometers).
- What is a datum? Datums are the basis for all geodetic survey work.
- What is the Sargasso Sea? The Sargasso Sea, located entirely within the Atlantic Ocean, is the only sea without a land boundary.
- How do we forecast harmful algal blooms? NOAA's Harmful Algal Bloom Operational Forecast System in the Gulf of Mexico identifies whether or not a bloom of algae is likely to contain a toxic species, where it is, how big it is, where it's headed, and if it could become more severe in the near future. Like a weather forecast, this system provides officials advance warning to test and close beaches and shellfish beds more precisely and for a shorter period of time.
- What are Christmas tree worms? You won't find Spirobranchus giganteus, also known as the Christmas tree worm, eating your fir tree this year. The common name for these worms is derived from their appearance, not their habitat or diet.
- Does coral jewelry make a good gift? orals have long been popular as souvenirs, for home decor, and in jewelry, but many consumers are unaware that these beautiful structures are made by living creatures. Fewer still realize that corals are dying off at alarming rates around the world.Coral reefs are some of the most biologically rich and economically valuable ecosystems on Earth, but they are increasingly threatened by pollution, invasive species, fishing, disease, bleaching, and global climate change.
- What is the cryosphere? The cryosphere is the frozen water part of the Earth system.
- Where do I get NOAA tides and currents data? Tide and current data is available from NOAA's Center for Operational Products and Services website.
- What is a turkeyfish? 'Turkeyfish' is another name for lionfish.
- What is Digital Coast? The Digital Coast is a cost-effective resource for coastal communities. Through the Digital Coast, users can find the information they need to explore the implications of sea level rise, conduct risk and vulnerability assessments, develop community green infrastructure plans, and much more. The site also provides valuable case studies to highlight how data and tools available from the Digital Coast have been used to address coastal management issues.
- How do I get NOAA nautical charts? The latest NOAA nautical charts and chart-related publications are available on the Office of Coast Survey website.
- What is the law of the sea? Notable in the development of the law of the sea are two international conventions signed in the latter half of the 20th Century.  One, the United Nations Convention on the Territorial Sea and the Contiguous Zone (1958), outlined the rights and responsibilities of States parties in their offshore waters.  In 1982, the United Nations Convention on the Law of the Sea further outlined the role of States parties in their marine areas and beyond.
- What makes the green turtle...green? Adult green turtles are herbivores, which means they eat only plants such as seagrasses and algae. This diet is thought to give them their greenish-colored fat, hence the name, the green turtle.
- What is a historical map or chart? The Office of Coast Survey maintains a historical map and chart collection of over 35,000 scanned, high-resolution images. The collection includes some of the nation’s earliest nautical charts, bathymetric maps, city plans, and Civil War battlefield maps.
- What is ghostfishing? Derelict fishing gear, sometimes referred to as "ghost gear," is any discarded, lost, or abandoned, fishing gear in the environment. This gear continues to fish and trap animals, entangle and potentially kill marine life, smother habitat, and act as a hazard to navigation. Derelict fishing gear, such as nets or traps and pots, is one of the main types of debris impacting the marine environment today.
- Are sea cucumbers vegetables? Found only in salt water, more than a thousand species of  sea cucumbers exist around the world. These squishy invertebrates are  echinoderms, making them distant relatives to starfish and urchins. Unlike  starfish or sea urchins, the bodies of sea cucumbers are covered with soft,  leathery skin instead of hard spines.
- What is the Storm QuickLook? When NOAA's National Weather Service issues a tropical storm warning for the U.S. or its territories, the Storm QuickLook is activated. This free online tool is a snapshot of near real-time coastal and weather observations for  areas affected by a storm.
- What is the difference between weather and climate? We hear about weather and climate all of the time. Most of us check the local weather forecast to plan our days. And climate change is certainly a "hot" topic in the news. There is, however, still a lot of confusion over the difference between the two.
- How did the Pacific Ocean get its name? In 1519, Portuguese explorer Ferdinand Magellan, in the employ of Spain, began a journey across the Atlantic Ocean to seek a western route to the Spice Islands via South America.
- Is there gold in the ocean? Yes, there is gold in the ocean.                  Ocean waters do hold gold – nearly 20 million tons of it.  However, if you were hoping make your fortune mining the sea, consider this: Gold  in the ocean is so dilute that its concentration is on the order of parts per trillion. Each liter of seawater  contains, on average, about 13 billionths of a gram of gold.
- Are starfish really fish? Sea stars, commonly called, "starfish," are not fish.
- What are jellyfish made of? Fascinating, elegant, and mysterious to watch in the water,  take a jellyfish out of the water, and it becomes a much less fascinating blob.  This is because jellyfish are about 95 percent water.
- Why are aquatic plants so important? The health of submerged aquatic vegetation is an important environmental indicator of overall ocean and estuary health.
- What is seaweed? Some seaweeds are microscopic, such as the  phytoplankton that live suspended in the water column and provide the  base for most marine food chains. Some are enormous, like the giant kelp that grow  in abundant “forests” and tower like underwater redwoods from their roots at  the bottom of the sea. Most are medium-sized, come in colors of red, green, brown,  and black, and randomly wash up on beaches and shorelines just  about everywhere.
- How can you tell the difference between an oil slick and an algal bloom? While it's relatively common to spot unidentified dark or reddish patches on the surface of the ocean in coastal areas around the U.S., it's not always easy to discern by sight what the substance is that's creating the disturbance.Often, offshore patches of discolored water are the result of algal blooms or oil slicks. Algal blooms occur when colonies of algae&mdash;simple ocean plants that live in the sea&mdash;grow out of control. While algal blooms come in many colors (and some have no color at all), they are popularly known as 'red tides' because some are deep red in color.Oil slicks, on the other hand, are simply films of oil floating on top of the water. While some slicks may be a few inches thick, most are thinner than a human hair. They may form naturally, but they are often introduced by man in incidents ranging from refined fuels or crude oil spilled from a ship to larger events such as last year's Deepwater Horizon oil spill. Oil sometimes emulsifies under certain conditions. Emulsified oil is a mixture of oil and water that often resembles chocolate mousse or pudding.How do you tell the difference? It can be difficult. Even the experts can be fooled, especially when looking at the ocean from an aircraft.
- How did the Hawaiian Islands form? The Earth&rsquo;s outer crust is made up of a series of tectonic  plates that move over the surface of the planet. In areas where the plates come  together, sometimes volcanoes will form. Volcanoes can also form in the middle  of a plate, where magma rises upward until it erupts on the sea floor, at what  is called a &ldquo;hot spot.&rdquo;
- Do the Great Lakes have tides? Water levels in the Great Lakes have long-term, annual, and short-term variations. Long-term variations depend on precipitation and water storage over many years. Annual variations occur with the changing seasons. There is an annual high in the late spring and low in the winter. These changes occur at a rate that can be measured in feet per month.
- How much of the ocean have we explored? For all of our reliance on the ocean, 95 percent of this  realm remains unexplored, unseen by human eyes.
- What is lightering? Lightering is the process of removing oil or other hazardous chemicals from a compromised vessel to another vessel to prevent oil from spilling into the surrounding waters.
- What is air gap? The NOAA Air Gap system is a tool that measures the clearance between the water surface and the bridge.
- What is a marine national monument? The main difference between national  marine sanctuaries and marine national monuments is the designation process and  the laws under which they are established. Sanctuaries are designated by  the Secretary of Commerce, through NOAA, under the National Marine Sanctuaries  Act (NMSA). The NMSA requires extensive public process, local community  engagement, stakeholder involvement, and citizen participation, both prior to and  following designation.
- What is VDatum? VDatum stands for Vertical Datum Transformation, an innovative and evolving software tool under development by NOAA's National Ocean Service. Free to the public, VDatum's primary purpose is to convert elevation data from various sources into a common reference system.
- What is a salt marsh? Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides.
- What is Natural Resource Damage Assessment? Natural Resource Damage Assessment (NRDA) is the process that federal agencies like NOAA, together with the states and Indian tribes, use to evaluate the impacts of oil spills, HAZMAT incidents and hazardous waste sites, and ship groundings on natural resources both along the nation's coast and throughout its interior.
- What threats do seabirds face? Learn more about the many threats that seabirds face along our coasts.
- What's the difference between a seal and a sea lion? Have you ever wondered about the main differences between seals and their &quot;second cousins,&quot; the sea lions?
- How does pressure change with ocean depth? At sea level, the air that surrounds us presses down on our bodies at 14.7 pounds per square inch (1 bar). You don't feel it because the fluids in your body are pushing outward with the same force.
- What is NERRS? The National Estuarine Research Reserve System is a network  of 28 areas representing different biogeographic regions of the United States.  The reserves are protected for long-term research, water quality monitoring,  education, and coastal stewardship. Each reserve is managed on a daily basis by  a lead state agency or university, with input from local partners. NOAA  provides funding, national guidance, and technical assistance.
- Are coral animals or plants? Corals are sessile, which means that they permanently attach themselves to the ocean floor, essentially "taking root" like most plants do. We certainly cannot recognize them by their faces or other distinct body parts, as we can most other animals.            So what are corals, anyway?
- What ocean basin has the most corals? Reef-building corals are restricted in their geographic  distribution by factors such as the temperature and the salinity (salt content)  of the water. The water must also be clear to permit high light penetration.
- What is the EEZ? The EEZ includes waters three to 200  miles (five to 322 kilometers) offshore (or nine to 200 miles &ndash; 14.5 to 322  kilometers &ndash; offshore in western Florida and Texas). Coastal states are  responsible for inshore waters out to three miles (five kilometers) of the  coast (or nine miles, 14.5 kilometers, off the west coast of Florida and off  Texas).
- What is the geoid? While we often think of the earth as a sphere, our planet is actually very bumpy and irregular.                   The radius at the equator is larger than at the poles due to the long-term effects of the earth's rotation.&nbsp; And, at a smaller scale, there is topography&mdash;mountains have more mass than a valley and thus the pull of gravity is regionally stronger near mountains.
- How do we monitor tides? Part of each station is a recorder which sends an audio  signal down a half-inch-wide sounding tube and measures the time it takes for  the reflected signal to travel back from the water's surface.
- What is a navigation response team? NOAA's navigation response teams,  part of the Office of Coast Survey, conduct hydrographic surveys of the ocean floor,  monitoring for changes   in depth or hazards below the surface of the water that  could pose   great danger to vessel traffic above.
- Why is the ocean salty, but rivers flowing into it are not? In  the beginning, the primeval seas were probably only slightly salty. But over  time, as rain fell to the Earth and ran over the land, breaking up rocks and  transporting their minerals to the ocean, the ocean has become saltier.
- What is the difference between a dolphin and a porpoise? People use the terms dolphins, porpoises, and whales to  describe marine mammals belonging to the order Cetacea (from the Greek work ketos, &ldquo;large sea creature&rdquo;), and often  use them interchangeably. The orca, or killer whale, for example, is actually  the largest member of the dolphin family.
- What is marine forensic science? The NOAA Marine Forensics Program is the only laboratory in the country dedicated to the forensic analysis of marine species.          The group'��s mission began in the 1970s when congress passed a series of acts that protect fisheries, marine mammals, and endangered species. The problem then arose of how to enforce these new laws. Without the fins, scales, and heads attached, it was impossible for NOAA agents to tell if the samples they came across were from regulated species.
- What is an invasive species? Invasive species can harm both the natural resources in an  ecosystem as well as threaten human use of these resources. An invasive species  can be introduced to a new area via the ballast water of oceangoing ships,  intentional and accidental releases of aquaculture species, aquarium specimens  or bait, and other means.
- Why does the ocean get colder at depth? Cold water has a higher density than warm water. Deep water gets colder at depth because cold, salty ocean water sinks to the bottom of the ocean basins. Less dense, warmer water rises to the surface. This process of rising and sinking water creates a complex pattern of ocean circulation called the 'global conveyor belt.'
- What makes the right whale "right"? The right whale is the most endangered species of whale off the  coast of the United States. It was the first whale hunted by American whalers,  and it was so depleted that it has not recovered despite being protected for  over 50 years.
- How long is the U.S. shoreline? As there is no reference that designates one specific  shoreline as the &ldquo;legal&rdquo; shoreline, numbers for the length of the U.S.  shoreline can vary depending on how the shoreline is defined.&nbsp;
- Where is the largest estuary in the United States? The Chesapeake Bay is the largest estuary in the United States and is one of the most productive bodies of water in the world.
- What is an eddy? The ocean is a huge body of water that is constantly in motion.  General patterns of ocean flow are called currents.  Sometimes theses currents can pinch off sections and create circular currents of water called an eddy.
- What is the difference between a hurricane, a cyclone, and a typhoon? Hurricanes, cyclones, and typhoons are all the same weather phenomenon;  we just use different names for these storms in different places. In the  Atlantic and Northeast Pacific, the term &ldquo;hurricane&rdquo; is used. The same type of  disturbance in the Northwest Pacific is called a &ldquo;typhoon&rdquo; and &ldquo;cyclones&rdquo; occur  in the South Pacific and Indian Ocean.
- What is the largest sea turtle? Weighing in at between 550 and 2,000 pounds (250 to 907 kilograms) with lengths of  up to six feet, the leatherback is a big turtle! Leatherback sea turtles can be  distinguished from other species of sea turtle by its lack of a hard shell or  scales. Instead, leatherbacks are covered with a firm, rubbery skin.
- Why is data on currents important? With predicted, real-time, and  forecasted currents, people can safely dock and undock ships, maneuver them in  confined waterways, and safely navigate through coastal waters. This helps to  avoid ship collisions or delay the arrival of goods.
- What is a waterspout? Waterspouts fall into two categories: fair weather waterspouts and tornadic waterspouts.
- What is the significance of the NOAA logo? In 1970, NOAA was officially recognized and all of its components  were united under a common name and mission. One year later, NOAA's first  administrator, Dr. Robert White, gave NOAA employees the choice of three  designs to be the official emblem for the new agency.
- What is the Loop Current? The loop current is an area of warm water that travels up from the Caribbean, past the Yucatan Peninsula, and into the Gulf of Mexico. The current is also known as the Florida current as it flows through the Florida Strait, into the Gulf Stream, and heads north up the eastern coast of the U.S.
- What is a seamount? Seamounts &mdash; undersea mountains formed by volcanic activity &mdash; were once thought to be little more than hazards to submarine navigation. Today, scientists recognize these structures as biological hotspots that support a dazzling array of marine life.
- Can penguins fly? Penguins are birds, so they do have wings. However, the wing  structures of penguins are evolved for swimming, rather than flying in the  traditional sense. Penguins do &ldquo;fly&rdquo; underwater at speeds of up to 15 to 25 miles per  hour.
- How does oil impact marine life? Oil  destroys the insulating ability  of fur-bearing mammals, such as sea otters, and the water-repelling abilities  of a bird's feathers, thus exposing these creatures to the harsh elements.  Without the ability to repel water and insulate from the cold water, birds and  mammals will die from hypothermia.
- What is the Great Pacific Garbage Patch? Debris found in this area can easily be ingested by marine species  causing choking, starvation, and other impairments.
- How is bathymetric data used? Bathymetric data, which includes information about the depths and shapes of underwater terrain, has a range of uses.
- How do sanctuaries protect marine life? National marine sanctuary staff  conduct research and use that science to better understand the marine  environment at all 14 sanctuary sites. This knowledge is  necessary to establish an effective strategy for protection.
- What are brain corals? Warmer water temperatures can result in coral bleaching. When water is too  warm, corals will expel the algae (zooxanthellae) living in their tissues   causing the coral to turn completely white. This is called coral bleaching. When  a coral bleaches, it is not dead. Corals can survive a bleaching event, but they  are under more stress and are subject to mortality.
- Are dolphins fish? Even though they live in the ocean all of the time, dolphins are mammals, not fish.
- What is bathymetry? The term &ldquo;bathymetry&rdquo; originally referred to the ocean&rsquo;s  depth relative to sea level, although it has come to mean &ldquo;submarine  topography,&rdquo; or the depths and shapes of underwater terrain.
- What is bioluminescence? The light emitted by a bioluminescent organism is produced  by energy released from chemical reactions occurring inside (or ejected by) the  organism.
- What is a tidal wave? A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth. The term “tidal wave” is often used to refer to tsunamis; however, this reference is incorrect as tsunamis have nothing to do with tides.
- Do alligators live in the ocean? There are many things you may encounter when swimming in the  ocean. Alligators probably aren&rsquo;t one of them.
- Is sea level the same all across the ocean? Most people are surprised to learn that, just as the surface  of the Earth is not flat, the surface of the ocean is not flat, and that the  surface of the sea changes at different rates around the globe. For instance,  the absolute water level height is higher along the West Coast of the United  States than the East Coast.
- How is ocean observing data used? NOAA orchestrates the collection of ocean data through a federal, regional, and private-sector partnership called the U.S. Integrated Ocean Observing System, or IOOS&reg;. This system helps the nation track, predict, manage, and adapt to changes in our  marine environment.
- What is the Bermuda Triangle? For decades,  the Atlantic Ocean&rsquo;s fabled Bermuda Triangle has captured the human imagination  with unexplained disappearances of ships, planes, and people.
- What is the National Spatial Reference System? NOAA&rsquo;s National Geodetic Survey (NGS) defines and maintains  the NSRS. The NSRS includes a network of permanently marked points; a  consistent, accurate, and up-to-date national shoreline; a network of Continuously  Operating Reference Stations (CORS) which supports three-dimensional  positioning activities; and a set of accurate models describing dynamic,  geophysical processes that affect spatial measurements.
- Where is all of the Earth's water? Of the three percent of the water that is not in the ocean,  about 69 percent is locked up in glaciers and icecaps. Ninety percent of that  frozen water is in Antarctica and about nine percent covers Greenland. Of the remaining freshwater, 30 percent of it is groundwater,  captured below our feet. About 0.3 percent is found in rivers and lakes. This  means that the water source we are most familiar with in our everyday lives,  rivers and lakes, accounts for less than one percent of all freshwater that exists on Earth.
- What is federal consistency? The Coastal Zone Management Act (CZMA), passed in 1972 and  administered by the Office  of Ocean and Coastal Resource Management, provides for the management of  the nation&rsquo;s coastal resources by balancing economic development with  environmental conservation. The goal of the CZMA is to &ldquo;preserve, protect, develop, and where possible, to restore or enhance  the resources of the nation's coastal zone.&quot;
- What is the smallest ocean? With an area of about 5.4 million square miles, the Arctic  Ocean is about 1.5 times as big as the United States. It is bordered by  Greenland, Canada, Norway, Alaska, and Russia. The average depth of the Arctic  Ocean is 12,000 feet and it is 17,850 feet at its deepest point.
- Do whales make noise? Whales are very social creatures that travel in groups  called &ldquo;pods.&rdquo; They use a variety of noises to communicate and socialize with  each other. The three main types of sounds made by whales are clicks, whistles,  and pulsed calls.
- What are the three main types of coral reefs? The most common type of reef is the fringing reef. This type  of reef grows seaward directly from the shore. They form borders along the shoreline  and surrounding islands. When a fringing reef continues to grow upward from a  volcanic island that has sunk entirely below sea level, an atoll is formed.  Atolls are usually circular or oval in shape, with an open lagoon in the  center. Barrier reefs are similar to fringing reefs in that they  also border a shoreline; however, instead of growing directly out from the  shore, they are separated from land by an expanse of water. This creates a  lagoon of open, often deep water between the reef and the shore.
- Where is the largest protected area in the National Marine Sanctuary system? The Papahānaumokuākea Marine National Monument is not only the largest conservation area in the U.S., it's one of the largest marine conservation areas in the world. It's larger than all of  America&rsquo;s national parks combined! This vast region preserves many of  Hawaii&rsquo;s Northwestern Islands and is made up of 139,797 square miles of reefs,  atolls, shallow waters, and deep seas.
- What lives in a kelp forest? In kelp forests, the most commonly found invertebrates are  bristle worms, scud, prawn, snails, and brittle stars. These animals feed on  the holdfasts that keep kelp anchored to the bottom of the ocean and algae that  are abundant in kelp forests. Sea urchins will often completely remove kelp  plants by eating through their holdfasts. Other invertebrates found in kelp  forests are sea stars, anemones, crabs, and jellyfish.
- What is maritime heritage? Maritime heritage includes not only physical resources such  as historic shipwrecks and prehistoric archaeological sites, but also archival  documents and oral histories. Maritime heritage can also include the stories of  indigenous cultures that have lived and used the oceans for thousands of years.
- How do we measure currents? An observer stands on a ship,  throws the drifter into the water, and then measures the time that it takes  that object to move along the side of a ship. As technology improved over time,  oceanographers began using mechanical current meters. A ship would deploy a  meter and usually some sort of rotor would turn and measure the currents. This  is still the basic process today; however there are more accurate and  sophisticated instruments.
- What was the first national marine sanctuary to be designated? The Monitor was  the first of 14 marine protected areas that make up the National Marine  Sanctuary System, which includes more than 388,498 square kilometers (150,000  square miles) of marine and Great Lakes waters. The sanctuary boundaries (2.59  square kilometers or 1 square mile) protect the wreck of the USS Monitor, which lies 25.75 kilometers (16  miles) southeast of Cape Hatteras, NC. Since its sinking in 1862, the Monitor has become a productive  artificial reef.
- What threats do coastal communities face? Losses from catastrophic events such as hurricanes can be extensive.  The economic losses from the 2005 hurricane season, which included Hurricanes  Katrina and Rita, were $200 billion, the costliest season ever. For some threats, such as sea level rise, only the projected  economic losses are indicated. For example, the vast majority of our nation&rsquo;s  commercial and recreational fisheries are dependent on coastal marshes.  Approximately two-thirds of those fisheries spend some stage of their lives in  tidal marshes. As sea levels rise, the built-up areas behind these marshes will  provide no opportunities for wetlands to migrate. The net result will be  billions of dollars in economic impacts affecting the livelihoods and  sustainability of many coastal communities.
- Are all algal blooms harmful? Less than one percent of algal blooms actually produce toxins.  Harmful algal blooms are blooms of species of algae that can have negative  impacts on humans, marine and freshwater environments, and coastal economies.  These blooms occur when phytoplankton, which are tiny microscopic plants, grow  quickly in large quantities while producing toxic or harmful effects on people,  fish, shellfish, marine mammals, and birds.
- Did I find a lost underwater civilization? With the advent of online mapping tools such as Google Earth, exploring our planet is easier than ever before. Recently, many of these tools have been updated to provide  detailed seafloor mapping data, or bathymetry.
- Why do we study tides? Scientists measure the times, heights, and extents of both  the inflow and outflow of the tidal waters that support a number of different  aspects of our daily lives. Navigating ships safely through shallow water  ports, intracoastal waterways, and estuaries requires knowledge of the time and  height of the tides as well as the speed and direction of the tidal currents.  Mariners need accurate data because the depths and widths of the channels and  increased marine traffic leaves very little room for error.
- What is geodesy? Many organizations use geodesy to map the U.S. shoreline,  determine land boundaries, and improve transportation and navigation safety. To  measure points on the Earth&rsquo;s surface, geodesists assign coordinates (similar  to a unique address) to points all over the Earth. In the past, geodesists determined  the coordinates of points by using Earth-based surveying tools to measure the distances  between points. Today, geodesists use space-based tools like the Global  Positioning System (GPS) to measure points on the Earth&rsquo;s surface.
- What are PCBs? These chemicals were banned in the U.S. in 1979 amid  suggestions that PCBs could have unintended impacts on human and environmental  health. From the 1920s until their ban,  an estimated 1.5 billion  pounds of PCBs  were made for things such as microscope oils, electrical  insulators, capacitors, and electric appliances such as television sets or  refrigerators. PCBs were also sprayed on dirt roads to keep the dust down prior  to knowing some of the unintended consequences from widespread use.&nbsp;
- What is the difference between land cover and land use? Land cover data documents how much of a region is covered by  forests, wetlands, impervious surfaces, agriculture, and other land and water  types. Water types include wetlands or open water. Land use shows how people use  the landscape &ndash; whether for development, conservation, or mixed uses. The  different types of land cover can be managed or used quite differently.
- What is nutrient pollution? This process is also known as eutrophication. Excessive  amounts of nutrients can lead to more serious problems such as low levels of  oxygen dissolved in the water. Severe algal growth blocks light that is needed  for plants, such as seagrasses, to grow. When the algae and seagrass die, they  decay. In the process of decay, the oxygen in the water is used up and this  leads to low levels of dissolved oxygen in the water. This, in turn, can kill fish,  crabs, oysters, and other aquatic animals.
- What is resilience? A community that is more informed and prepared will have a  greater opportunity to rebound quickly from weather and climate-related events,  including adapting to sea level rise. The ability to rebound more quickly can  reduce negative human health, environmental, and economic impacts.
- What is an environmental sensitivity index map? An environmental sensitivity index (ESI) map compiles  information for coastal shoreline sensitivity, biological resources, and human  resources. This information is used to create cleanup strategies before an accident occurs so that  authorities are prepared to take action in the event of such a spill. Advance planning  reduces the harmful consequences of oil spills and cleanup.
- What is a dead zone? Less oxygen dissolved in the water is often referred to as a  &ldquo;dead zone&rdquo; because most marine life either dies, or, if they are mobile such  as fish, leave the area. Habitats that would normally be teeming with life  become, essentially, biological deserts.
- What is a national marine sanctuary? Ranging in size from less than 2.6 square kilometers to 356,880 square  kilometers (one square mile to 137,792  square miles), each sanctuary site is a unique place needing special  protections. Marine sanctuaries are natural classrooms, cherished recreational  spots, and valuable commercial industries.
- What can I do to protect coral reefs? There are many things you can do to protect coral reefs!
- What is remote sensing? Remote sensors collect data by detecting the energy  that is reflected from Earth. These sensors can be on satellites or mounted on  aircraft.
- What is ecosystem science? An ecosystem is an ecological community comprised of  biological, physical, and chemical components, considered as a unit.
- How frequent are tides? A lunar day is how long it takes for one point on the Earth  to make one complete rotation and end up at the same point in relation to the  moon. The reason that a lunar day is longer than a normal 24-hour day is because  the moon rotates around the Earth in the same direction that the Earth is  spinning. It takes the Earth an extra 50 minutes to &ldquo;catch up&rdquo; to the moon.
- What are phytoplankton? Phytoplankton, also known as microalgae, are similar to  terrestrial plants in that they contain chlorophyll and require sunlight in  order to live and grow. Most phytoplankton are buoyant and float in the upper  part of the ocean, where sunlight penetrates the water. Phytoplankton also require  inorganic nutrients such as nitrates, phosphates, and sulfur which they convert  into proteins, fats, and carbohydrates.
- What is a guyot? A guyot is a seamount, or undersea mountain. Seamounts are formed by volcanic activity and can be taller than  3,000 meters (10,000 feet). &nbsp;They can be  isolated or part of large mountain chains. The New England Seamount contains  more than 30 peaks that stretch 1,600 kilometers (994 miles) from the coast of  New England.
- Who first charted the Gulf Stream? Although first observed in 1513 by Ponce de Leon, the Gulf  Stream was not charted until the early 1770s by Benjamin Franklin, with the  help of a Nantucket sea captain.
- How do people use kelp? Algin, an emulsifying and bonding agent, is extracted from  kelp and used in these products. Kelp is also used as food on mollusk farms.  Between 100,000 and 170,000 wet tons of kelp are harvested from California  waters each year.
- What is the biggest fish in the ocean? Whale sharks can grow to 15 meters (50 feet) and weigh as much as 40 tons by some estimates! They have broad, flat heads with short snouts and their  backs have an interesting white, yellow, and grey checkerboard pattern. Whale  sharks can live up to 100 years.
- Do sharks eat people? Only about a dozen of the more than 300 species of sharks  have been involved in attacks on humans. Sharks evolved millions of years  before humans existed and therefore humans are not part of their normal diets.  Sharks primarily feed on smaller fish but some species prey upon seals, sea  lions, and other marine mammals.
- What is "smart growth"? Smart growth is a way of approaching community development  and expansion with the goal of making them &ldquo;more livable, more economically  efficient, and more effective at meeting the needs of the people who live  there.&rdquo;
- What is the largest ocean basin on Earth? Covering approximately 155 million square kilometers (59  million square miles) and containing more than half of the free water on Earth,  the Pacific is by far the largest of the world&rsquo;s ocean basins. All of the  world&rsquo;s continents could fit into the Pacific basin.
- Can humans drink seawater? Seawater contains salt. When humans drink seawater, their  cells are thus taking in water and salt. While humans can safely ingest small  amounts of salt, the salt content in seawater is much higher than what can be  processed by the human body. Additionally, when we consume salt as part of our  daily diets, we also drink liquids, which help to dilute the salt and keep it at  a healthy level. Living cells do depend on sodium chloride (salt) to maintain  the body&rsquo;s chemical balances and reactions; however, too much sodium can be  deadly.
- Where are marine protected areas located? There are over 1,700 marine protected areas, or MPAs, in the  U.S. that cover approximately 34 percent of marine waters. MPAs are found in  every region of the United States. The West Coast (California, Oregon, and  Washington) has the highest number of MPAs; however, the region with the  largest area of MPAs is the Pacific Islands. This is because of the designation  of the Papahānaumokuākea Marine National Monument, which is one of the largest  marine conservation areas in the world.&nbsp;&nbsp;
- What is IOOS? IOOS coastal and marine data (e.g., water temperature, water  level, currents, winds, and waves) are collected by many different tools  including satellites, buoys, tide gauges, radar stations, and underwater  vehicles. A variety of tools is needed to collect data on global, national,  regional, and local levels. Some of these tools are in the water collecting data  while others may be on land or in space. Most of the data collected are  streamed to a database, making them easier to access.
- What are El Nino and La Nina? El Ni&ntilde;o and La Ni&ntilde;a are opposite phases of what is known as the El Ni&ntilde;o-Southern Oscillation (ENSO) cycle. The ENSO cycle is a scientific term that describes the fluctuations in temperature between the ocean and atmosphere in the (approximately between the International Date Line and 120 degrees West). La Ni&ntilde;a is sometimes referred to as the cold phase of ENSO and El Ni&ntilde;o as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.
- What is a kelp forest? Kelp forests can be seen along much of the west coast of North America. Kelp are  large brown algae that live in cool, relatively shallow waters close to the shore. They grow in dense groupings much like a forest on land.  These underwater towers of kelp provide food and shelter for thousands of fish, invertebrates, and marine mammal species.
- What is the global ocean conveyor belt? The great ocean conveyor moves water around the globe.
- What is a coral reef made of? Stony corals (or scleractinians) are the corals primarily  responsible for laying the foundations of, and building up, reef structures.  Massive reef structures are formed when each individual stony coral organism &ndash;  or polyp &ndash; secretes a skeleton of calcium carbonate.
- How is sea level rise related to climate change? Many  people are interested in climate change and how a changing climate will affect  the ocean. With the majority of Americans living in coastal states, rising  water levels can have potentially large impacts. Scientists have determined that  global sea level has been steadily rising since  1900 at a rate of at least 1 to 2.5   millimeters (0.04 to 0.1 inches) per year.
- What is a mangrove forest? There are about 80 different species of mangrove trees. All  of these trees grow in areas with low-oxygen soil, where slow-moving waters  allow fine sediments to accumulate. Mangrove forests only grow at tropical and  subtropical latitudes near the equator because they cannot withstand freezing  temperatures.
- Is change important to estuaries? Estuaries are tidally driven. Tides flush the system and  provide nutrients to keep food webs functional. By doing this, tides create  constantly changing conditions of exposure to air or increased levels of water  in an estuarine environment. Because of tides, the water levels in an estuary  are going up and down several times a day.
- What types of plants and animals live in an estuary? Estuaries - areas where fresh and saltwater mix - are  made up of  many different types of habitats. These habitats can include oyster reefs,  coral reefs, rocky shores, submerged aquatic vegetation, marshes, and  mangroves. There are also different animals that live in each of these  different habitats. Fish, shellfish, and migratory birds are just a few of the  animals that can live in an estuary.
- What does an oceanographer do? Oceanography covers a wide range of topics, including marine  life and ecosystems, ocean circulation, plate tectonics and the geology of the  sea floor, and the chemical and physical properties of the ocean.
- What is a rip current? Rip currents are powerful, narrow channels of fast-moving water that are prevalent along the East, Gulf, and West coasts of the U.S., as well as along the shores of the Great Lakes.
- Are lionfish a threat to Atlantic Ocean fish? Lionfish are native to the Indo-Pacific and Red Sea, but are now established along the eastern coast of the U.S. from Florida to North Carolina. They are also  regularly found throughout the Bahamas and northern Caribbean, and have  been sighted as far south as Nicaragua and as far east as the U.S.  Virgin Islands.
- What is upwelling? Winds blowing across the ocean surface push water away. Water  then rises up from beneath the surface to replace the water that was pushed  away. This process is known as &ldquo;upwelling.&rdquo; Upwelling occurs in the open ocean and along coastlines. The  reverse process, called &ldquo;downwelling,&rdquo; also occurs when wind causes surface  water to build up along a coastline and the surface water eventually sinks  toward the bottom.
- What is marine snow? As plants and animals near the surface of the ocean die and  decay, they fall toward the sea floor, just like leaves and decaying material  fall onto a forest floor. In addition to dead animals and plants, marine snow  also includes fecal matter, sand, soot, and other inorganic dust. The decaying material is referred to as &ldquo;marine snow&rdquo;  because it looks a little bit like white fluffy bits.
- What do the numbers mean on a nautical chart? Soundings are water depth measurements that indicate how  deep the water is in a particular area in either feet or fathoms. A fathom is a  nautical unit of measurement and is equal to six feet.
- How long does it take to produce a nautical chart? Nautical  charts show what is in, under, and around the water, to help mariners transit  our waters safely. The time it takes to develop a new nautical chart varies and  it depends on the intensity of the ship travel in the area and the availability of  resources to develop the new chart.
- Can the ocean freeze? Ocean water freezes just like freshwater, but at lower temperatures. Fresh water freezes at 0 degrees Celsius (32 degrees Fahrenheit), but seawater freezes at about -1.9 degrees Celsius (28.4 degrees Fahrenheit) because of the salt in it.  When seawater freezes,  however, the ice contains very little salt because only the water part freezes. It can be melted down to use as drinking water.
- What is a tsunami? Tsunamis are giant waves caused by earthquakes or volcanic eruptions under the sea.      Out in the depths of the ocean,  tsunami waves  do  not dramatically increase in height. But as the  waves travel inland, they  build up to higher and higher heights as the depth of  the ocean decreases. The  speed of tsunami waves depends on  ocean depth rather than the distance  from the source of the wave. Tsunami waves may travel as fast as jet planes over deep waters, only slowing down when reaching shallow waters. While  tsunamis are often  referred to as tidal waves,   this  name is discouraged by oceanographers because tides have little to do with these giant waves.
- What is marine debris? Each year, three times as much rubbish is dumped into the world's oceans as the weight of fish caught. Marine debris injures and kills marine life,  interferes with navigation safety, and poses a threat to human health. Our oceans and  waterways are  polluted with a wide variety of marine debris ranging  from soda cans and plastic bags to derelict fishing gear and abandoned vessels.&nbsp;
- What is a current? Ocean currents are driven by wind, temperature changes, and tides
- Can marine debris degrade on its own in the environment? Human-made products are not completely biodegradable.  These products will take a long time, possibly hundreds of years, to degrade.  Some products such as glass never degrade. To determine how long it will take  for debris to degrade depends on several factors such as material type, size,  thickness, and environmental conditions (e.g., amount of exposure to sunlight  or location - on the beach or floating at sea).
- What does peanut butter have to do with the ocean? When it comes to eating, the ocean provides much more than just  seafood. Many of the foods and products found in your local grocery store  contain ingredients from the ocean.
- In what types of water do corals live? Reef-building corals cannot tolerate water temperatures  below 64&deg; Fahrenheit (18&deg; Celsius). Many grow optimally in water temperatures  between 73&deg; and 84&deg; Fahrenheit (23&deg;&ndash;29&deg;Celsius), but some can tolerate  temperatures as high as 104&deg; Fahrenheit (40&deg; Celsius) for short periods.
- How fast is the Gulf Stream? The Gulf Stream is an intense, warm ocean current in the  western North Atlantic Ocean. It moves north  along the coast of Florida and then turns eastward off of North Carolina,  flowing northeast across the Atlantic.
- What is the largest living structure on Earth? Stretching for 1,600 miles (2,600 kilometers) over an area  of approximately 133,000 square miles (344,400 square kilometers), the Great Barrier Reef is the largest coral reef system in  the world. The reef is located off the coast of Queensland,  Australia, in the Coral Sea.
- What's the difference between an ocean and a sea? Many people use the  terms &quot;ocean&quot; and &quot;sea&quot;  interchangeably when speaking about the ocean, but  there is a difference between the two  terms when speaking of geography (the study of the Earth's surface).
- What are the seven seas? The origins of the phrase 'Seven Seas'    can be traced  to ancient times. In various cultures at different times in history, the Seven Seas has  referred  to bodies of water  along trade routes,  regional  bodies of water, or exotic and far-away  bodies of water.
- What percentage of marine areas are protected? There are over 1,700 marine protected areas (MPAs) in the  United States established by federal, state, and territorial governments. These  areas cover 34 percent of U.S. marine waters and vary widely in their purpose,  legal authorities, managing agencies, and level of protection.
- Where can I get tide predictions? The Center for Operational Oceanographic Products and  Services (CO-OPS) is primarily responsible for predicting and measuring water  levels and currents and disseminating this information. CO-OPS collects,  analyzes, and distributes such data to maintain safe maritime navigation and  waterborne commerce.
- What is an iceberg? To be classified as an iceberg, the height of the ice must  be greater than 16 feet (five meters) above sea level and the thickness must be  98-164 feet (30-50 meters) and the ice must cover an area of at least 5,382  square feet (500 square meters).
- What is a hydrothermal vent? Underwater volcanoes at spreading ridges and convergent plate boundaries produce hot springs known as hydrothermal vents.
- What is an extremophile? Extremophiles are microorganisms with the ability to thrive in extreme environments such as hydrothermal vents.
- What is coastal zone management? The concept of coastal zone management is a relatively new  one, emerging less than four decades ago from the need to tackle an array of  interconnected problems associated with population growth and development along  our nation&rsquo;s coasts.
- Do volcanoes occur in the ocean? Volcanic eruptions occur only in certain places and do not  occur randomly. This is because the Earth&rsquo;s crust is broken into a series of  slabs known as tectonic plates. These plates are rigid, but they &ldquo;float&rdquo; on a  hotter, softer layer in the Earth's interior. As the plates move, they spread  apart, collide, or slide past each other.
- What is a rogue wave? Rogues, called  'extreme storm waves' by scientists, are those waves which are greater than twice the size of surrounding waves, are very  unpredictable, and often  come unexpectedly from directions other than prevailing wind and waves.
- What can the ocean teach us about life on other planets? Life on Earth is found in conditions ranging from the coldest  arctic ice to  extremely hot hydrothermal systems on the ocean  floor. Microbes are also found in very acidic conditions, very salty  conditions, and very alkaline conditions. These microbes are   called &ldquo;extremophiles&rdquo; (which means 'lovers of extremes').           While conditions on the  surface of the Earth where humans are happy are likely to be extremely  rare outside of our home planet, the range of conditions in which  microbes are found on Earth are more likely to be found on other  planets and moons.
- Where is the highest tide? The highest tides in the world can be found in Canada at the Bay of Fundy, which separates New Brunswick from Nova Scotia.
- What are tides? Tides are very long-period waves that move through the oceans in response to the forces exerted by the moon and sun. Tides originate in the oceans and progress toward the coastlines where they appear as the regular rise and fall of the sea surface.
- Why do we have oceans? Most scientists agree that the atmosphere and the oceans accumulated  gradually over millions and millions of years with the continual &lsquo;degassing&rsquo; of  the Earth&rsquo;s interior.
- How many oceans are there? While  there is only one global ocean, the seas are  geographically divided into the Atlantic,  Pacific, Indian, Arctic, and Southern (Antarctic) Oceans.
- How does sound travel in the ocean? Some people may think that because it is easier  to hear in air than in water, then sound must travel faster in air. Actually,  sound travels five times faster in water than in air.
- Why is the ocean blue? The ocean  is blue because water absorbs colors in the red part of the light spectrum.  Like a filter, this leaves behind colors in the blue part of the light spectrum  for us to see.
- How much water is in the ocean? It's hard to imagine, but an astounding 97 percent of the Earth's water can be found in our oceans.
- What is a nautical chart? A nautical chart is one of the most fundamental tools available to the mariner. It's a graphic portrayal of the marine environment showing the nature and form of  the coast, the general configuration of the sea bottom, including water depths, locations of dangers to navigation, locations and characteristics of human-made aids to navigation and other features useful to the mariner.
- Why is the ocean salty? Salt in the ocean comes from rocks on land.
- What is a marine protected area? Marine protected areas (MPAs) in the U.S. come in a variety of forms and are established and managed by all levels of government. There are marine sanctuaries, estuarine research reserves, ocean parks, and marine wildlife refuges. Each of these sites differs. MPAs may be established to protect ecosystems, preserve cultural resources such as shipwrecks and archaeological sites, or sustain fisheries production.
- What's the difference between a tide and a current? Tides are driven by the gravitational force of the moon and sun. Tides are characterized by water moving up and down over a long period of time. When used in association with water, the term &quot;current&quot; describes the motion of the water.
- Why do Harmful Algal Blooms occur? Harmful algal blooms (HABs)  occur when colonies of algae&mdash;simple ocean plants that live in the sea&mdash;grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals and birds.
- What is a red tide? Harmful algal blooms, or HABs, occur when colonies of algae&mdash;simple ocean plants that live in the sea&mdash;grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal.
- What do coral reefs have to do with medicine? Coral reefs are sometimes considered the medicine cabinets of the 21st century.
- What is the biggest source of ocean pollution? Eighty percent of pollution to the marine environment comes from the land. One of the biggest sources is called nonpoint source pollution, which occurs as a result of runoff.
- How far does light travel in the ocean? Sunlight entering the water may travel about 1,000 meters (3,280 feet) into the ocean under the right conditions, but there is rarely any significant light beyond 200 meters (656 feet).
- What percentage of the American population lives near the coast? Coastal areas are home to a wealth of natural and economic  resources and are the most developed areas in the nation. The narrow fringe  comprising 17 percent of the contiguous U.S. land area is home to more than  half of the nation's population.
- How much of the ocean have we explored? For all of our reliance on the ocean, 95 percent of this  realm remains unexplored, unseen by human eyes.
- What's the difference between a nautical chart and a map? A nautical  chart provides a very detailed and accurate representation of the coastline,  which takes into account varying tidal levels and water forms, critical to a  navigator.
- What is a sonar? Sonar, short for Sound Navigation and Ranging, is helpful for exploring and mapping the ocean because  sound  waves travel farther in the water than do  radar  and light waves.
- What species live in and around coral reefs? Coral reefs are home to millions of species. Hidden beneath the ocean waters, coral  reefs teem with life. Fish, corals, lobsters, clams, seahorses, sponges, and  sea turtles are only a few of the thousands of creatures that rely on reefs for  their survival.
- What is hydrography? Hydrography  is the science that deals with the measurement and description of the physical  features of bodies of water and the land areas that are affected by those  bodies of water.
- How important is the ocean to our economy? The U.S. economy is very dependent on the health of the ocean. Consider the following facts: Through the fishing and boating industry, tourism and recreation, and ocean transport, one out of six jobs in the U.S. is marine-related.
- What role does the Ocean Service play with our nation's aircraft and airports? You may be surprised to learn that the National Ocean Service is responsible for surveying  in support of the nation's  airports and airspace.
- What role does the ocean play in the weather? The  ocean plays an important role in shaping our climate and weather patterns.
- Is sea level rising? There is strong evidence that global sea level is now rising at an increased rate and will continue to rise during this century.
- How do coral reefs protect life and property? The  coral reef structure buffers shorelines against waves, storms and floods, helping  to prevent loss of life, property damage and erosion. When reefs are damaged or  destroyed, the absence of this natural barrier can increase the damage to  coastal communities from normal wave action and violent storms.
- What is the longest mountain range on earth? The longest mountain range on Earth is called the mid-ocean ridge. Spanning  65,000 kilometers (40,389 miles) around the globe, it's truly a global landmark.
- What is a benthic habitat map? The term benthic refers to anything associated with or occurring on the bottom of a body of water. The animals and plants that live on or in the bottom are known as the benthos.           In ocean waters, nearshore and estuary areas are most frequently mapped. This is partly because the areas are shallow enough to map, but also because these areas are very important to preserve and manage.            Benthic habitat maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. The resulting digital map is viewed using geographic information system tools.
- What is an estuary? Estuaries  and their surrounding wetlands are bodies of water usually found where rivers  meet the sea. Estuaries are home to unique plant and animal communities that  have adapted to brackish water &mdash; a mixture of fresh water draining from the  land and salty seawater.
- How do coral reefs benefit the economy? Healthy coral reefs support commercial and subsistence fisheries as well as jobs and businesses through tourism and recreation. Approximately half of all federally managed fisheries depend on coral reefs and related habitats for a portion of their life cycles. The National Marine Fisheries Service estimates the commercial  value of U.S. fisheries from coral reefs is over $100 million.
- How deep is the ocean? The average depth of the ocean is about 4,267 meters (14,000 feet).  The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the  southern end of the Mariana  Trench, which runs several hundred  kilometers southwest of the U.S.  territorial island   of Guam. Challenger Deep  is approximately  11,030 meters (36,200 feet) deep.