Cerulean Seas Environments

This page lists basic explanations of environmental effects and various terrains in the Cerulean Seas setting.

## Light Zones

The ocean can be divided from its surface to its depth into three zones based on the amount of light received. They are:

**Sunlit Zone:** This is the top layer, nearest the surface. Here there is enough light penetrating the water to support photosynthesis. More than ninety percent of all marine life lives in the sunlit zone. The sunlit zone goes down about 600 feet.

Most fish and other sentient races live in this zone.

**Twilight Zone:** Only a small amount of light can penetrate the water at this depth. As the water becomes deeper, the pressure also increases.

Plants do not grow here. Only animals that have adapted to low light survive. The nommo and the Cerulean nixie call this zone home. This gloomy part of the ocean begins at about 600 feet under the water and extends to the darkest part, which begins about 3000 feet down. Bioluminescent creatures abound in this zone.

**Midnight Zone:** Ninety percent of the ocean is in the midnight zone. It is oppressively dark, the water pressure is extreme, and the temperature is near freezing. Living creatures found here live close to cracks in the planet's crust. These cracks give off mineral-rich materials that nourish bacteria, which form the bottom of the food chain here, much like plankton does in the waters above. Deep drow, the aquatic equivalent of the surface dark elves, claim this realm as their own.

\*Creatures with low-light vision can see objects twice as far away as the given distance.

## Topography

The ocean floor is not as flat and sandy as their more-familiar beaches, nor quite so predictable. In addition to the aquatic mountains, valleys, deserts, and plains, there are features that are foreign to those that live solely on land.

As the land descends beneath the sea, there are drastic changes in the planet's geology. This transitional area, known as the continental margin, includes both the continental shelf and the continental slope. As dry-land fades from sight, the heavy and thick continental granite gives way to a thinner layer of basalt.

The continental shelf normally contains water that is only a couple of hundred feet deep. The neritic zone is located here. The width of the continental shelf varies greatly depending on location. At the edge of the continental shelf, the ocean floor begins a steep descent known as the continental slope. This area is often pervaded by fathomless submarine canyons.

The slope levels out at the ocean basin, which also has some interesting features. Perhaps the most unusual are the abyssal plains which are large, flat areas on the ocean floor covered with a thick layer of sediment and decomposing organic ooze. Large, undersea volcanoes called seamounts occasionally rise from these depths. Sometimes the peaks of these giant underwater volcanoes reach to the surface to form volcanic islands.

Ocean trenches are found along the edge of ocean basins. These trenches contain the deepest parts of the ocean, and therefore, the deepest parts of the world. They can go down several miles, and are known to harbor the most terrible abominations that one could imagine.

## Tides

Tides are the periodic rising and falling of large bodies of water. The gravitational attraction of the moon causes the oceans to bulge out in the direction of the moon. Another bulge occurs on the opposite side, since the planet is also being pulled toward the moon (and away from the water on the far side). Ocean levels fluctuate daily as the sun, moon and planet interact. As the moon travels around the planet and as they, together, travel around the sun, the combined gravitational forces cause the world's oceans to rise and fall. Since the planet is rotating while this is happening, two tides occur each day.

Each day, there are two high tides and two low tides. The ocean is constantly moving from high tide to low tide, and then back to high tide. There are about 12 hours and 25 minutes between the two high tides.

When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides which are called spring tides. When the sun and moon are not aligned, the gravitational forces cancel each other out, and these tides, known as neap tides, are not as dramatically high and low.

**Spring Tides:** When the moon is full or new, the gravitational pull of the moon and sun are combined. At these times, the high tides are very high and the low tides are very low. This is known as a spring high tide or spring tide. Spring tides do not have anything to do with the season however; they are just exceptionally strong tides.

The Proxigean Spring Tide is a rare, unusually high tide. This very high tide occurs when the moon is both at its proxigee (closest point) and in the new moon phase. The proxigean spring tide occurs at most once every 1.5 years.

**Neap Tides:** During the moon's quarter phases the sun and moon work at right angles, causing the bulges to cancel each other. The result is a smaller difference between high and low tides and is known as a neap tide. Neap tides are especially weak tides. They occur when the gravitational forces of the moon and the sun are perpendicular to one another (with respect to the planet). Neap tides occur during quarter moons.

**The Tidal Effect:** In a world with little land, tides can be an important factor. The average tide moves the shoreline 20 to 50 feet, with rare tides or locations changing it even more. This could leave the tops of undersea cities (which are usually built near the shore) to be periodically exposed, stationary objects and creatures to become temporality beached, and dry-land objects to become suddenly submerged. A clever adventurer can use the tides to his advantage, although these advantages are equally available to the villains of the world.

## Terrain

The sea has a large variety of terrain, each with its own challenges and features. Listed below are a few examples of common terrain encountered in an aquatic setting.

### **BEACH TERRAIN**

Beaches consist of a sandy or rocky shore, usually with very sparse vegetation, if any. The beach is home to a variety of sea creatures who take advantage of easy access to land and water.

The Table 1-7 describes in general terms how likely it is that a given square has a terrain element in it.

**Boulder:** Boulders come in many shapes and sizes, but are generally 1d6×5 feet tall and cover 1d6 squares. Beach boulders can be quite slippery, especially if they rest below the high-tide line. A Climb skill check, DC 15, is required to navigate such a rock successfully while walking upon them. If the boulder is underwater, the character can swim over it without penalty.

**Driftwood:** Wood of all varieties washes up along the beach regularly. It has a characteristically worn appearance including smooth and twisted shapes and sun-bleached pallor. It can form huge piles that act as natural barriers. Moving into these barriers both above and below the water costs one square. It also provides low cover.

**Dune:** Dunes are steep piles of loose sand that are often formed by water currents or wind. Dunes are usually around 4d6×5 feet long, and 1d4×5 feet tall. Dunes cost four squares of movement to climb and two squares of movement otherwise. Dunes also increase the DC of Acrobatics checks by 2.

Creatures that run or charge down a dune must first succeed on an Acrobatics skill check, DC 10, or slide downwards another 1d3 squares. If the check fails by more than 4, the character also falls prone at the end of the slide.

Underwater sand dunes are called sand bars, and work the same way if the character is moving along the sea floor. However, a character can also swim over these features without movement penalty.

**Rubble:** This consists of all manner of stone, wood, animal, plant and artificially-made debris that have gathered into large tangled piles on the beach. The DC of Acrobatics skill checks increases by 2 in these areas. Rubble can exist both above and below the water

**Sand, loose:** This is either soft, dry sand or wet sand that has been recently churned up and not allowed to settle. It costs 2 squares of land movement to enter a square with loose sand. If underwater, characters can swim over them without penalty.

**Sand, packed:** This is wet sand that has settled into firm ground. There are no movement penalties in this area.

**Standing water:** Standing water exists on beaches most often from seawater becoming trapped during low tide. This results in shallow pools, usually no more than a foot deep and 1d6×5 feet in diameter. It costs 2 squares of movement to enter a square with standing water and the DC of Acrobatics skill checks increases by 2. Standing pools are typically too shallow to effectively swim in.

**Surf, heavy:** Heavy surf describes fiercely surging water about 5 feet in depth. It costs 4 squares of movement to enter a square of heavy surf, for both swimming and walking. Acrobatics checks automatically fail in areas of heavy surf. It is also very likely to contain a riptide (20%) or undertow (35%), both of which are described previously in this chapter under the heading of “Water Currents.” Heavy surf occurs in a long line parallel to the shore, with light surf resting between the heavy surf and the shore.

**Surf, light:** Light surf is rapidly surging water less than three feet in depth. The DC of Acrobatics skill checks increases by 2 in these areas. It costs 2 squares of movement to enter a square of light surf, and it is too shallow to effectively swim in. Areas of light surf are also 20% likely to have an undertow.

**Stealth and Detection on a Beach:** Sandy beaches offer very limited cover. The maximum distance at which a Perception check to detect the nearby presence of others can succeed is 6d6 × 20 feet. Rocky beaches usually have more cover, reducing this distance to 4d6 × 20 feet.

### **CORAL REEF TERRAIN**

Coral reefs are usually encountered in warm waters and are made up of thousands of different varieties of living coral. They are home to countless sea creatures and are very rich in biodiversity.

Coral reefs generally occur in water that is 1d8 × 10 feet deep, and can grow to a height of up to 1d8 × 5 feet tall, so long as this remains at least five feet below the water’s surface. Although rare, deepwater coral reefs also exist as far down as 300 feet, and are usually lit with spectacular bioluminescence. A coral reef itself, regardless of depth, can be anywhere from 20 feet to several miles in diameter. It also occurs in narrow strips that can be only a few feet wide, but several miles long.

The Cerulean Seas campaign setting features several coral reef systems despite being in a temperate zone. This is due to a high degree of volcanic activity and thermal vents that keep some areas warm enough to support tropical ecosystems.

The Table 1-8 describes in general terms how likely it is that a given square has a terrain element in it. It is divided into shallow reefs, where the top of the coral is fifteen feet or less from the water’s surface, and deep reefs, where the top of the coral and the water’s surface exceeds a distance of fifteen feet.

**Coral, dead:** Living coral reefs are built upon dead coral (calcium-rich skeletons of living coral). It is usually pale and worn, often appearing as irregularly shaped stone. Navigating areas of dense dead coral can be tricky. It costs two squares of movement to enter a square with dead coral, and the DC Acrobatics skill checks increases by 4.

**Coral, living:** Entering the area of a living coral reef can be extremely dangerous for any creature of Small size or greater. It is inhabited by all manner of living spines, branches, stingers, and tentacles. A creature entering a square containing living coral much make an Acrobatics skill check, DC 10, or get scratched, stung, or stabbed by the coral. Treat this effect as a slashing melee attack with a +4 attack bonus that deals 1d3 points of damage. Any creature damaged by the coral must also make a DC 14 Fortitude save or contract the fire coral disease (detailed later in this chapter).

**Coral, surfacing:** Surfacing coral is mostly dead coral that reaches up beyond five feet below the water’s surface. It is periodically exposed to the air from the action of waves and tide. Due to its irregular formation and shallow depth, it is impossible to swim through an area of surfacing coral. Walking is possible, though it costs 4 squares of movement to enter an area with this feature. Acrobatics checks in this area automatically fail.

**Pass:** Passes are meandering cracks and spaces between the coral, usually with a sandy bottom that is also devoid of coral. A pass is typically 1d8 × 5 feet wide. They range from 10 to 100 feet long, and often branch out to several other passes forming a huge labyrinth.

**Pit:** Much like a pass, a pit is a gap in the coral the leads to a sandy bottom. It is usually five feet in diameter, and can go down 1d8 × 5 feet. This can be an unforeseen obstacle while walking along the top of the coral. A DC 10 Perception skill check is required to notice a pit. Failure to notice a pit means a walking character is now swimming, and subject to the rules of buoyancy. If the pit occurs in an area of living coral, the unwary character will also be subject to being scraped by the coral as if entering the square for the first time.

**Sand:** Sand can cover areas of dead coral, or exist at the bottom of passes and pits. It creates no barrier to movement.

**Surf, heavy & light:** These are essentially the same features that are found on beaches, except that they carry the added risk of being injured by coral or coral fauna. A character entering a square containing heavy surf amid a coral reef must make an Acrobatics skill check, DC 14, or get attacked by the coral as if entering a square of living coral. In light surf, this DC is reduced to a DC of 12.

**Stealth and Detection in a Coral Reef:** Characters walking on top of a surfacing coral reef are out in the open. In this case the distance at which a Perception skill check to detect the presence of others can succeed is 6d6 × 20 feet. Submerged characters can find an abundance of hiding places within the reef making the encounter distance only 1d6 × 10 feet.

### **ICEBERG TERRAIN**

An iceberg is a gigantic block or mass of ice that has broken off from a glacier or ice shelf. This iceberg then floats in the world's oceans and moves via wind and ocean currents. Icebergs are famous for their size and their ability to hide it under water. Typically, only one-tenth of an iceberg's volume is visible above the water's surface, while most of its mass is below. In general, the total size of the average iceberg is 1d10 × 25 feet above sea level, with another 9d10 × 25 feet below sea level. They are typically 1d12 × 50 feet across. Icebergs can be several miles across and several hundred feet tall, however. These super-sized icebergs often break up into smaller icebergs when they reach warm waters. Despite their size, icebergs move an average speed of 10 miles per day, which equates to a speed of around 5 feet per round.

Even though the Cerulean Seas are over one thousand miles from a glacial shelf, they do harbor a strong Antarctic current known as the Cerulean Current. This is the same stream that brought the Lochgelly selkies and their wondrous iceberg city to the realm. Occasionally, other normal icebergs wander in and are often quickly harvested by the selkies before they inevitably melt away as they get trapped in the warmer waters of the Cerulean Seas. Icebergs, especially the large ones, have been known to travel thousands of miles before finally breaking apart completely and melting.

The Table 1-9 describes in general terms how likely it is that a given square has a terrain element in it. It is divided into growlers (less than 100 feet across), standard icebergs (more than 100 feet across, but less than 2000 feet across), and super icebergs (more than 2000 feet across).

Icebergs have a special terrain element, the ice wall, which is marked on the border between squares rather than taking up a square itself.

TABLE 1-9: ICEBERG TERRAIN
 Crevasse
 Pool
 Slope, gradual
 Slope, steep

**Cliff:** This is similar to the terrain feature of the same name described in Hills Terrain section of chapter 13 of the Pathfinder Roleplaying Game, but they are typically 1d10 × 10 feet tall. Cliffs taller than 60 feet take up 20 feet of horizontal space.

**Crevasse:** A crevasse is an irregular crack in the ice caused by ocean currents, shifting winds, or large air pockets in the ice. An average crevasse is anywhere from 3d10 × 10 feet long and 1d4 × 25 feet deep (sometimes deep enough to reach the water below), and 5d6 feet wide. A character falling into a crevasse drops into the water or onto the ice at the bottom. In addition, the steep, slick sides of the crevasse offer little opportunity to climb out of the crevasse unaided (Climb skill check, DC 30). Some crevasses are hidden by thin crusts of ice; a character approaching a hidden crevasse is entitled to a Perception skill check, DC 20, to notice the crevasse before stepping into it, although running or charging characters do not get to make this check.

**Ice wall:** A vertical plane of ice, an ice wall requires a DC 30 Climb check to ascend. A typical ice wall is 1d8 × 10 feet tall on standard icebergs, and 2d10 × 10 feet tall on super icebergs. Ice walls occur on the edges of squares, not in the squares themselves.

**Pool:** Melting icebergs often accumulate large pools of freshwater in their valleys, flat surfaces, and at the bottom of their crevasses. These pools are shallow, usually no more than five feet deep and 1d6×5 feet in diameter. It costs 2 squares of movement to enter a square with a pool and the DC of Acrobatics skill checks increases by 3. Pools are typically too shallow to swim in.

**Slope, gradual and steep:** These function as described in the Hills Terrain section of chapter 13 of the Pathfinder Roleplaying Game, except that Acrobatic skill checks have +2 to their difficulty due to slippery ice.

**Stealth and Detection on an Iceberg:** The maximum distance in iceberg terrain at which a Perception check for detecting the nearby presence of others can succeed is 4d10 × 10 feet. Standing at a high point of the iceberg may provide a better vantage point, however.

### **KELP FOREST TERRAIN**

Kelp forests can be seen along much of the coasts of the Cerulean Seas. Kelp is large brownish-green seaweed that lives in cool, shallow waters close to the shore. It grows in thick groupings much like a forest on land. These submerged towers of kelp provide sustenance and shelter for thousands of fish, invertebrates, and marine mammal species. In fact, kelp forests harbor a greater assortment of plants and animals than nearly any other aquatic community. Many creatures use the thick blades of kelp as a safe shelter from predators for their young or from stormy weather.

A square of kelp forest costs 2 squares of movement to enter. Any creature in a square of kelp forest has concealment. A creature more than 1 square away in kelp forest has total concealment. The top of a kelp forest is generally 1d20 × 5 feet from the surface of the water and can grow to a height of 1d8×10 feet from the sea floor. Some varieties of kelp can grow hundreds of feet long. Kelp forests can be anywhere from a few hundred feet to several miles in size.

**Stealth and Detection in a Kelp Forest:** The maximum distance at which a Perception check to detect the nearby presence of others can succeed is 1d8 × 10 feet, due to the heavy cover provided by this massive seaweed.

### **MARSH TERRAIN**

Marshes include tidal marshes, saltwater marshes, and freshwater swamps. They are fully described in Chapter 13 of the Pathfinder Roleplaying Game.

### **OPEN WATER TERRAIN**

Most of the world’s ocean is open water. This area is equivalent to a vast and featureless desert. The only visible feature is light itself. From below, sunlight shimmers through the waves at the surface. From above, one can see the light sink into shadowy depths. These elements provide a creature adapted to this environment with a backdrop against which it can attempt to hide. In order to use the gloom below or glow above for concealment, an individual must be within 25 feet of the surface and above the viewer, or at least 100 feet deep and below the viewer.

The open ocean is typically 1d10 × 200 feet deep, but can also go down several miles. The average seafloor in open water is usually made up of featureless sand, muck, or ooze.

**Stealth and Detection in Open Water:** The maximum distance at which a Perception skill check to detect the nearby presence of others can succeed is 4d10 × 10 feet. Unless a character can get above or below an opponent, there is no concealment to be found.

### **SARGASSUM**

Sargassum is free-floating seaweed found several miles offshore in gigantic brownish-green mats throughout the Cerulean Seas. These mats of vegetation provide crucial habitat for a wide variety of marine animals in the open ocean. Occasionally, they grow so dense that they can be walked upon; though doing so is extremely treacherous and risks entanglement. The profusion of rotten seaweed common to sargassum mats often attracts hideous scavenging monsters as well.

Sargassum mats are typically 1d10 × 20 feet in size (though they can also be as narrow as five to ten feet wide and go on in miles-long streamers). Sargassum comes in two varieties: sparse and thick.

TABLE 1-10: SARGASSUM TERRAIN
 Mat, sparse
 Mat, thick
 Pass

**Carcass or Wreck:** Occasionally, gigantic creatures get caught in the sargassum mass while trying to surface for air. Ships may also run into this mire of seaweed and become hopelessly entangled. Either result is the same— a rotting hulk is left behind. Aside from leaving a stinking, slime covered vantage point that raises above the seaweed about 10 to 20 feet, these features have little value.

**Mat, sparse:** Sparse sargassum is very difficult to walk on. Characters must spend 4 squares of movement in order to enter a square of sparse mat. Charging and running are not possible. The mat is about five feet thick. Dense tangles of seaweed hang below the mat at a depth of up to twenty feet, thus obstructing swimmers who must spend 2 squares of movement to enter a square of sparse mat.

A Medium creature that ends its move on a square of sparse mat must succeed on a DC 15 Acrobatics skill check or break through. A Large creature that enters a square of sparse mat must succeed on a DC 25 Acrobatics skill check or break through. Huge or larger creatures break through automatically.

Creatures that break through the sparse mat also make a Reflex savings throw or gain the entangled condition. Entangled creatures may attempt to break free as a move action, making a Strength or Escape Artist check. The DC is based on the creature’s size; Medium-size or smaller creatures have a DC of 12, Large have a DC of 15, Huge and larger creatures have a DC of 20. Each failed check while still within the sargassum adds an additional 2 points to the DC, as more and more seaweed adds to the entanglement.

If a creature breaks through a sparse mat, it creates a patch of open water equal to its space. In addition, climbing out of the water onto the mat again is difficult; a creature trying to climb back on top of a square of sparse mat must succeed on another Acrobatics check at the same DC, or it fails to climb up out of the water.

**Mat, thick:** Characters must spend 2 squares of movement in order to enter a square of thick sargassum mat and the DC of Acrobatics checks increases by 5. The mat is about ten feet thick, and the seaweed trails up to fifty feet below to hinder swimmers, who must spend 2 squares of movement to enter a square of thick mat.

A Large creature that ends its move on a square of thick mat must succeed on a DC 15 Acrobatics check or break through. Huge or larger creatures break through automatically. They are affected as if passing through a light mat, but the DC both to avoid becoming entangled and to break free from an entanglement increases by 4.

**Pass**: A pass is an expanse of open water in a sargassum mat. Characters walking on top of a sargassum mat must swim (or jump) across passes, while characters swimming through sargassum find easy passage. Passes are usually 1d6×5 feet wide and wind aimlessly amid the floating mats.

**Stealth and Detection in Sargassum:** Characters on top of the sargassum can detect others at a distance of 3d6 × 20 feet. Submerged, the maximum distance at which a Perception check to detect the nearby presence of others can succeed is 1d6 × 10 feet due to the heavy cover provided by the seaweed mat.

### **MISCELLANEOUS AQUATIC TERRAIN FEATURES**

There are some common features that can occur in nearly all aquatic terrains. Some of these features are listed below.

**Coral Wall:** Dead coral can be hewn into bricks and structures much like stone. When a coral wall divides two chambers, it is usually at least 3 feet thick in order to bear the weight of the coral above. It requires a DC 20 Climb check to climb a wall made of dead coral.

**Gravel:** Gravel bottoms are common in colder ocean waters, and are often inundated with many varieties of seaweed. While easier to maneuver through than muck, gravel bottoms are slicker than a clear sandy bottom. Walking creatures pay 2 squares of movement to enter each square of gravel bottom. Running and charging are impossible in this terrain feature, as there is no good way to get footing. The DC of Acrobatics skill checks increases by 5.

**Hydrothermal Vent:** Also called “hot springs” if they occur in shallow water, a hydrothermal vent is a fissure in the planet's surface from which geothermal-heated water issues. Hydrothermal vents are often found near volcanic activity, which is especially common in the north east Cerulean Sea and eastern Harper’s Isle. The temperature of these areas can range from pleasantly warm to scalding hot. In the case of the latter, squares that contain vents may be considered areas of severe or extreme heat (see Heat Dangers in Chapter 13 of the *Pathfinder Roleplaying Game Core Rulebook*).

**Muck:** Abyssal floors, estuaries, and tidewaters are commonly covered in muck up to three feet deep. Creatures on foot pay 4 squares of movement to enter each square of muck, and running and charging are impossible. The DC of Acrobatics skill checks increases by 5 in these areas.

**Rock Reef:** A rock reef is a quantity of underwater stone which is usually heavily overrun with anemones, barnacles, shellfish, and other small underwater creatures. A rock reef can function as a wall or steep slope underwater, although swimmers can simply go over or around them.

**Sand:** Submerged sand is usually quite waterlogged and well–packed. This provides better footing than gravel, but is still slow-going. Creatures on foot pay 2 squares of movement to enter each square of sandy bottom. The DC of Acrobatics checks increases by 2.