The abyssopelagic zone is the region of deep water from 4,000m to the ocean. This is a the deepest part of the pelagic zone other than the hadopelagic deep sea trenches. 

Zones of the ocean, including Abyssopelagic between 4,000 and 6,000 m (photo credit: seasky.org)


 This region is typically home to chemosynthetic bacteria, tubeworms, and small fish.  Occasional residents include sharks, shrimp, and squid.  Many of the organisms that live here are dark colored or transparent because no sunlight reaches this zone.