The bottom-most layer of the oceanic zone, lying below the abyssopelagic zone at depths greater than about 6,000 meters (19,680 feet); hadal zone: The hadopelagic zone is found in long and narrow topographic V-formed depressions or trenches in the sea. The name is derived from Hades, the classical Greek underworld. This particular layer is 90% unknown and very few species are known to live in the open areas, however many organisms exist in hydrothermal vents in this and other stratums.