Deepest marine biome

The bottom part of the pelagic zone (open sea, away from the coastline or sea floor) is known as the hadal zone. It covers deep ocean trenches, beginning at a depth of around 6,000 m (19,680 ft) and continuing to the ocean floor. This region is characterized by a complete lack of sunlight and pressure levels up to 986.9 atmospheres (1.01 tonnes per cm2/14,503 psi). Most animals at this depth are colourless, and use bioluminescence as a light source. This biome includes hydrothermal vents, whose heat and chemical nutrients have allowed bizarre varieties of life to exist, including the scaly-foot snail, which has iron-sulphide armour plating on its foot. The report of a fish living below 6,898 m (22,631 ft) depth is the deepest benthic capture of a vertebrate with corroborated depth data. Also, there is life at the bottom of the Mariana Trench: the deepest sample, taken at 10,918 m (35,820 ft), contained various species of bacteria.