Deep-Sea Floor (OSS)

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The deep-sea floor is the area directly beyond the continental margins. Generally, the sea floor lies at a depth of between 6,000 and 40,000 feet. Deep sea floors have five general geological characteristics: abyssal plains and hills, seamounts and guyouts, oceanic plateaus, trenches, and oceanic ridges.
Because of their unusual depth, sea floors will usually be dark, unexplored areas in most campaign worlds. Perhaps only a very few Fathomers or other wizards have even a glimmering of knowledge about these wondrous and hazardous areas. The unenlightened or superstitious call this area the home of sea monsters and other deadly creatures.
==Abyssal Plains and Hills==
Abyssal plains are generally flat areas of accumulated mud that exist seaward of continental rises. The floors of these plains usually contain large numbers of crustaceans, bottom feeders, skates, manta rays, ixitxachitl, eels, burrowing creatures, and other marine life specially adapted to life in the deep ocean. In fact, observant PCs can easily see the trails of such bottom organisms as they streak through the soft ooze and sediment of the abyssal plain.
Abyssal hills are small and relatively low, rarely extending more than a half-mile above the surrounding sea floor. Scattered throughout the abyssal plains, these hills are actually extinct submarine volcanoes covered with a thin layer of sediment. As such, they could easily contain small, naturally (or otherwise) hollowed out caves or rooms perfect for unusual encounters.
==Seamounts and Guyouts==
Like abyssal hills, seamounts and guyouts are extinct volcanoes that rise up from the abyssal plains. Seamounts possess a conical cross-section, while guyouts have flat tops resulting from erosion. Unlike abyssal hills, however, these volcanoes stand much taller than a half-mile. In fact, some seamounts soar as high as 13,000 feet above the sea floor.
Seamounts and guyouts usually exist in clusters or chains and are home to a wide variety of marine life. The bases of these formations sometimes possess caverns or hollowed areas.
==Oceanic plateaus==
Oceanic plateaus are broad expanses of stony sediment hundreds or thousands of miles long. They often rise more than a half mile above the surrounding sea floor. Oceanic plateaus offer the Dungeon Master an ideal area in which to place ancient ruins and sunken cities. It is quite possible for some specially adapted, intelligent marine species (perhaps a deep-dwelling sahuagin offshoot) to reside in these Atlantean-type structures.
==Trenches==
Trenches are V-shaped depressions in the abyssal plain. They have steep slopes (10 to 40 degrees) and can extend for several thousand miles. Trenches represent perhaps the greatest mystery to exploring PCs, as they sometimes descend as far as thirty-five thousand feet deep-a distance of almost seven miles. Dark mysteries and deadly creatures exist within the confines of deep trenches. Often, giant squid, kraken, and sea dragons choose trenches in the deepest, darkest waters for their lairs.
==Oceanic Ridges==
Oceanic ridges are broad expanses, or chains, of underwater mountains and volcanoes that can extend to a length of 30,000 miles. Thousands of rift valleys and cavern systems exist within any oceanic ridge. A wide variety of plants and animals (many of them magical and exotic) live within these geologic complexes.