On the long undersea plains of Rebma, there are chasms and crevasses and trenches. These gaps in the sea floor are particularly treacherous; they have become known collectively as the Deeps. The Abyss. They are cold, dark places, home to monsters.
In the Deeps, there is no trace of light from the surface, only the ghostly luminescence of sea creatures that hunt in the dark. The cold and pressure of the Abyss are so great that even native Rebmans risk their lives attempting to swim through them. The things that do live there are not sentient races for the most part, but are instead scavengers who seek out creatures that foolishly enter the Deeps, or predators who hunt the scavengers.
In certain places only spoken of cautiously, or else in reverent blasphemous worship, the Abyss holds sources of dark intelligence and power. Those who venture there do so at the cost of their immortal souls.
The Soldieve Deeps, a fathomless tear in the seabed placed at unusual proximity to the coastline of Amber, is the purported lair of Leviathan. The monstrous being is notable for having emerged from the Abyss at least twice in the history of Rebma, wreaking terrible destruction before 'he' is stopped. His existence as well as his whereabouts, are currently, worrisomely, unknown.