remiconnesson/oceanservice-noaa-facts huggingface dataset:
# Can marine debris degrade on its own in the environment?

## Most debris items take a long time to degrade in the marine environment.

![Photo of marine debris](/facts/marinedebris.jpg "Photo of various marine debris materials")

Many factors determine how long it will take for debris to degrade, such as material type, size, thickness, and environmental conditions.

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).

While photodegradable plastics (plastics capable of being broken down by light) may break down from its first state (or created state), these plastics never completely degrade, but actually divide into tiny pieces called microplastics. Microplastics are the multi-colored pieces of plastic that can be found in a handful of sand on the beach or in the ocean. Scientists are still investigating the impact of microplastics on our ocean and marine life.
# How many oceans are there?

## There is only one global ocean.

![World Map Showing One Global Ocean. (derived from: http://en.wikipedia.org/wiki/Sea#mediaviewer/File:World_ocean_map.gif)](/facts/world-ocean.gif "There is only one global ocean")

While there is only one global ocean, the vast body of water that covers 71 percent of the Earth is geographically divided into distinct named regions. The boundaries between these regions have evolved over time for a variety of historical, cultural, geographical, and scientific reasons.

Historically, there are four named oceans: the Atlantic, Pacific, Indian, and Arctic. However, most countries - including the United States - now recognize the Southern (Antarctic) as the fifth ocean. The Pacific, Atlantic, and Indian are the most commonly known.

The Southern Ocean is the 'newest' named ocean. It is recognized by the [U.S. Board on Geographic Names](http://geonames.usgs.gov/) as the body of water extending from the coast of Antarctica to the line of latitude at 60 degrees South. The boundaries of this ocean were proposed to the [International Hydrographic Organization](http://www.iho.int/) in 2000. However, not all countries agree on the proposed boundaries, so this has yet to be ratified by members of the IHO. The U.S. is a member of the IHO, represented by the NOS [Office of Coast Survey.](https://www.nauticalcharts.noaa.gov/)
# What does peanut butter have to do with the ocean?

VIDEO: What does peanut butter have to do with the ocean? Here's an overview in under two minutes. [Transcript](#transcript)

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.

For example, peanut butter and toothpaste both contain carrageenan. Carrageenan is a generic term for compounds extracted from species of red algae. Boiling the algae extracts the carrageenan, which in turn is used to make peanut butter more spreadable. Carrageenan also gives toothpaste its consistency and is used in other cosmetics, pharmaceuticals, and industrial products.

### Video Transcript

Did you know that your peanut butter is easier to spread because of an ingredient from the ocean? It's called Carrageenan and it comes from a species of red algae. Carrageenan is also found in toothpaste. Many foods, medicines, cosmetics, and other everyday products depend on things that are found in the ocean. So the next time you enjoy a peanut butter sandwich or brush your teeth, think about how the ocean gives people much more than just seafood and a fun place to take a vacation. Then think about what you can do in return.
# In what types of water do corals live?

## Because of strict environmental restrictions, coral reefs generally are confined to tropical and semi-tropical waters.

[![map of coral reef locations around the world](/facts/coralwaters.jpg "Coral reef locations around the world")](/facts/coralwaters-large.jpg)

Coral reef locations around the world. [Download](/facts/coralwaters-large.jpg)

Reef-building corals cannot tolerate water temperatures below 64° Fahrenheit (18° Celsius). Many grow optimally in water temperatures between 73° and 84° Fahrenheit (23°–29°Celsius), but some can tolerate temperatures as high as 104° Fahrenheit (40° Celsius) for short periods.

Most reef-building corals also require very saline ([salty](https://oceanservice.noaa.gov/facts/whysalty.html)) water ranging from 32 to 42 parts per thousand.

The water must also be clear so that a maximum amount of light penetrates it. This is because most reef-building corals contain photosynthetic algae, called zooxanthellae, which live in their tissues. The corals and algae have a unique relationship. The coral provides the algae with a protected environment and compounds they need for photosynthesis. In return, the algae produce oxygen and help the coral to remove wastes. Most importantly, zooxanthellae supply the coral with food. The algae need light in order to produce food via photosynthesis.
# Why is the ocean blue?

## The ocean acts like a sunlight filter.

![Big Sur coastline looking north to Bixby Canyon Bridge in California. ](/facts/oceanblue.jpg "Why is the ocean blue?")

Big Sur coastline looking north to Bixby Canyon Bridge in California.

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.

The ocean may also take on green, red, or other hues as light bounces off of floating sediments and particles in the water.

Most of the ocean, however, is completely dark. Hardly any light penetrates deeper than 656 feet, and no light penetrates deeper than 3,280 feet.
# How much water is in the ocean?

![sunset viewed from Kure Atoll, located near Midway Atoll in the Northwestern Hawaiian Islands](/facts/oceanwater.jpg "sunset viewed from Kure Atoll, located near Midway Atoll in the Northwestern Hawaiian Islands")

_The ocean covers more than 70 percent of the surface of our planet._

It's hard to imagine, but about 97 percent of the Earth's water can be found in our ocean. Of the tiny percentage that's not in the ocean, about two percent is frozen up in glaciers and ice caps. Less than one percent of all the water on Earth is fresh. A tiny fraction of water exists as water vapor in our atmosphere.

According to the [U.S. Geological Survey](https://www.usgs.gov/special-topic/water-science-school/science/how-much-water-there-earth?qt-science_center_objects=0#qt-science_center_objects), there are over 1,386,000,000 cubic kilometers (332,519,000 cubic miles) of water on the planet. A cubic mile is the volume of a cube measuring one mile on each side. Of this vast volume of water, NOAA's National Geophysical Data Center estimates that 1,335,000,000 cubic kilometers (321,003,271 cubic miles) is in the ocean.

That's enough water to fill about 352,670,000,000,000,000,000 gallon-sized milk containers!
# Why is the ocean salty?

![mussels growing in brine pool](/facts/ocean-salty.jpg "methane mussels growing 650 feet (198 meters) below the surface")

A [brine seep](https://flowergarden.noaa.gov/image_library/brineimages.html) located at the base of East Flower Garden Bank at a depth of about 240 feet. The seep lies within [Flower Garden Banks National Marine Sanctuary](https://flowergarden.noaa.gov/) in the Gulf of America (formerly Gulf of Mexico). It is formed from super-saline water flowing from [under the seafloor](https://flowergarden.noaa.gov/about/naturalsetting.html#domes). The image was taken by the ROV _Argus_ as part of the [Secrets of the Gulf Expedition](https://flowergarden.noaa.gov/image_library/brineimages.html) in March 2007. Credit: Sea Research Foundation and the Ocean Exploration Trust

Salt in the ocean comes from two sources: runoff from the land and openings in the seafloor.

Rocks on land are the major source of salts dissolved in seawater. Rainwater that falls on land is slightly acidic, so it erodes rocks. This releases ions that are carried away to streams and rivers that eventually feed into the ocean. Many of the dissolved ions are used by organisms in the ocean and are removed from the water. Others are not removed, so their concentrations increase over time.

Another source of salts in the ocean is hydrothermal fluids, which come from [vents in the seafloor](/facts/vents.html). Ocean water seeps into cracks in the seafloor and is heated by magma from the Earth’s core. The heat causes a series of chemical reactions. The water tends to lose oxygen, magnesium, and sulfates, and pick up metals such as iron, zinc, and copper from surrounding rocks. The heated water is released through vents in the seafloor, carrying the metals with it. Some ocean salts come from underwater volcanic eruptions, which directly release minerals into the ocean.

[Salt domes](https://flowergarden.noaa.gov/about/naturalsetting.html#domes) also contribute to the ocean's saltiness. These domes, vast deposits of salt that form over geological timescales, are found underground and undersea around the world. They are common across the continental shelf of the northwestern Gulf of America.

Two of the most prevalent ions in seawater are chloride and sodium. Together, they make up around 85 percent of all dissolved ions in the ocean. Magnesium and sulfate make up another 10 percent of the total. Other ions are found in very small concentrations. The concentration of salt in seawater (salinity) [varies with temperature, evaporation, and precipitation](https://www.climate.gov/news-features/featured-images/shifting-ocean-surface-saltiness-2004-2013). Salinity is generally low at the equator and at the poles, and high at mid-latitudes. The average salinity is about 35 parts per thousand. Stated in another way, about 3.5 percent of the weight of seawater comes from the dissolved salts.
# What is the Great Barrier Reef?

## The Great Barrier Reef is the largest living structure on Earth.

![Satellite photograph of the Great Barrier Reef situated off the northerastern coast of Australia.](/facts/gbrlargeststructure.jpg "What is the largest living structure on Earth?")

Satellite photograph of the Great Barrier Reef situated off the northeastern coast of Australia.

Stretching for 1,429 miles over an area of approximately 133,000 square miles , 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.

The reef, which is large enough to be visible from space, is made up of nearly 3,000 individual reefs. Much of the Great Barrier Reef is a [marine protected area](https://oceanservice.noaa.gov/facts/mpa.html), managed by the Great Barrier Reef Marine Park Authority of Australia.
# How far does light travel in the ocean?

Sunlight entering the water may travel about [1,000 meters](#) into the ocean under the right conditions, but there is rarely any significant light beyond [200 meters](#).

The ocean is divided into three zones based on depth and light level. The upper [200 meters](#) of the ocean is called the **euphotic**, or "**sunlight**," zone. This zone contains the vast majority of commercial fisheries and is home to many protected marine mammals and sea turtles.

Only a small amount of light penetrates beyond this depth.

The zone between [200 meters](#) and [1,000 meters](#) is usually referred to as the “**twilight**” zone, but is officially the **dysphotic** zone. In this zone, the intensity of light rapidly dissipates as depth increases. Such a minuscule amount of light penetrates beyond a depth of [200 meters](#) that photosynthesis is no longer possible.

The **aphotic** zone exists in depths below [1,000 meters](#). Sunlight does not penetrate to these depths and the zone is bathed in darkness. The aphotic zone is further subdivided into the **bathypelagic** zone (or **midnight** zone) between [1,000](#) and [4,000](#) meters, the **abyssopelagic** (or the **abyss**) between [4,000](#) and [6,000 meters](#), and the **hadopelagic** zone (or **hadal** zone) [6,000 meters](#) and deeper.

---

### Infographic Transcript: Distance Sunlight Travels in the Ocean

-   The left side of this graphic shows a measuring stick against a representation of the ocean; it shows three depths: sea level, 200 meters, and 1,000 meters and deeper.
-   The middle portion of the graphic shows the ocean divided into three zones. The first division from sea level to 200 meters is labeled as the euphotic (sunlight) zone and says "sunlight rarely penetrates beyond this zone." Graphic representations of tuna are shown swimming in this first zone. The second division from 200 meters to 1,000 meters is labeled as the dysphotic (twilight) zone and says "sunlight decreases rapidly with depth; photosynthesis is not possible here." Graphic representations of shrimp, swordfish, and hatchet fish are shown swimming in this second zone. The third division is labeled from 1,000 meters and deeper and is labeled as the aphotic zone and says "sunlight does not penetrate; the zone is bathed in darkness." Graphic representations of angler fish and giant squid are shown swimming in this zone.
-   The division labeled 'aphotic zone' contains this additional text: "The aphotic zone incudes: The bathypelagic (midnight) zone between 1,000-4,000 meters; the abyssopelagic (abyss) zone between 4,000-6,000 meters; and the hadopelagic (hadal) zone is 6,000 meters and deeper.
-   A solid blue thin line is at the bottom of the graphic shows the website address of the National Ocean Service and the NOAA logo.
# What is an extremophile?

## An extremophile is an organism that thrives in extreme environments.

![Extreme Microbes from Hydrothermal Vents](/facts/extremophile.jpg "Extreme Microbes from Hydrothermal Vents")

Extremophiles are organisms that live in "extreme environments," under high pressure and temperature. Bacteria often form on the rocks near the hydrothermal vents. Pictured is the Sully Vent in the Main Endeavour Vent Field, NE Pacific. A bed of tube worms cover the base of the black smoker.

"Extremophiles" are organisms with the ability to thrive in extreme environments such as hydrothermal vents.  
Since they live in “extreme environments” (under high pressure and temperature), they can tell us under which range of conditions life is possible.

The unique enzymes used by these organisms, called "extremozymes," enable these organisms to function in such forbidding environments. These creatures hold great promise for genetically based medications and industrial chemicals and processes.

It's important to note that these organisms are 'extreme' only from a human perspective. While oxygen, for example, is a necessity for life as we know it, some organisms flourish in environments with no oxygen at all.
# What can the ocean teach us about life on other planets?

## Life in some parts of the ocean may be similar to conditions on other planets and moons.

![Tubeworms that grow near the boundary where hot vent fluid mixes with cold seawater on the ocean floor](/facts/extremebugs.jpg "What can the ocean teach us about life on other planets?")

Tubeworms that grow near the boundary where hot vent fluid mixes with cold seawater on the ocean floor are an example of extremophiles that broaden our perspective on where to look for life. Chemosynthetic bacteria living inside the tubeworms derive energy from chemicals emitted in the hot water of hydrothermal vents.

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 "extremophiles" (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.

Some areas of our oceans, for example, may be similar to conditions found elsewhere in the solar system.

Jupiter's moon Europa is completely covered by ice, but the tidal energy generated by giant Jupiter is so strong that a global ocean likely exists under the ice that could be 10 times as deep as what we find on Earth. Many scientists think that hydrothermal vents may exist at the bottom of this vast ocean.

This is exciting news, because microbes are found in abundance in hydrothermal vent systems in our oceans.

Understanding extreme life on Earth might help us identify environments on other moons and planets where life could exist.
# How do coral reefs protect lives and property?

## Coral reefs provide a buffer, protecting our coasts from waves, storms, and floods.

![a coral reef](/facts/coral-protect.jpg)

_Corals form barriers to protect the shoreline from waves and storms._

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.

Several million people live in U.S. coastal areas adjacent to or near coral reefs. Some coastal development is required to provide necessary infrastructure for coastal residents and the growing coastal tourism industry.

However, the impacts of coastal development (e.g., marina, dock, and bridge construction, dredging to replenish beaches) and polluted runoff from coastal areas can damage coral reefs over the long term. Therefore, the health of coral reefs depends on sustainable coastal development practices that protect sensitive coral ecosystems and the creatures that reside there.
# What is sonar?

## Sonar uses sound waves to 'see' in the water.

 [](soundscapes.mp4) 

A three-minute video about multibeam and side scan sonar, including a visualization that shows how sonar data is used to make products like nautical charts. | **Download**: [Soundscapes](soundscapes.mov) (75 MB)

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. NOAA scientists primarily use sonar to develop [nautical charts](nautical_chart.html), locate underwater hazards to navigation, search for and map objects on the seafloor such as shipwrecks, and map the seafloor itself. There are two types of sonar—active and passive.

## Active Sonar

**Active** sonar transducers emit an acoustic signal or pulse of sound into the water. If an object is in the path of the sound pulse, the sound bounces off the object and returns an “echo” to the sonar transducer. If the transducer is equipped with the ability to receive signals, it measures the strength of the signal. By determining the time between the emission of the sound pulse and its reception, the transducer can determine the range and orientation of the object.

## Passive Sonar

**Passive** sonar systems are used primarily to detect noise from marine objects (such as submarines or ships) and marine animals like whales. Unlike active sonar, passive sonar does not emit its own signal, which is an advantage for military vessels that do not want to be found or for scientific missions that concentrate on quietly “listening” to the ocean. Rather, it only detects sound waves coming towards it. Passive sonar cannot measure the range of an object unless it is used in conjunction with other passive listening devices. Multiple passive sonar devices may allow for triangulation of a sound source.
# Why do harmful algal blooms occur?

Harmful algal blooms (HABs) occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.

While we know of many factors that may contribute to HABs, how these factors come together to create a 'bloom' of algae is not well understood.

Studies indicate that many algal species flourish when wind and water currents are favorable.

In other cases, HABs may be linked to 'overfeeding.' This occurs when nutrients (mainly phosphorus, nitrogen, and carbon) from sources such as lawns and farmlands flow downriver to the sea and build up at a rate that 'overfeeds' the algae that exist normally in the environment.

Some HABs have also been reported in the aftermath of natural phenomena like sluggish water circulation, unusually high water temperatures, and extreme weather events such as hurricanes, floods, and drought.

People often get sick by eating shellfish containing toxins produced by these algae. Airborne HAB toxins may also cause breathing problems and, in some cases, trigger asthma attacks in susceptible individuals.

HABs can also be costly in economic terms as well. At present, HABs cause about $82 million in economic losses to the seafood, restaurant, and tourism industries each year. HABs reduce tourism, close beaches and shellfish beds, and decrease the catch from both recreational and commercial fisheries.

NOAA scientists continue to monitor and study HABs to determine how to detect and forecast the location of the blooms. The goal is to give coastal communities advance warning, so they can adequately plan and deal with the adverse environmental and health effects associated with a harmful bloom.
# How deep is the ocean?

## The average ocean depth is 3,682 meters (12,080 feet).

![Active hydrothermal vents with yellows and dark patterns actively releasing plumes into the surrounding water.](deepocean-960.jpg)

_Active "smoker" hydrothermal vent chimneys about 9 meters tall are found deep in the Mariana Arc region in the Western Pacific Ocean. Credit: Pacific Ring of Fire 2004 Expedition. NOAA Office of Ocean Exploration; Dr. Bob Embley, NOAA PMEL, Chief Scientist._

The average depth of the ocean is about 3,682 meters (12,080 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 10,935 meters (35,876 feet) deep](https://doi.org/10.1016/j.dsr.2021.103644). It is named after the HMS _Challenger_, whose crew first sounded the depths of the trench in 1875.