1. Pertaining to the biogeographic realm of the ocean, or living in the depths of the ocean: The bathypelagic realm of the large open water areas of the world lies between the mesopalagic and the abyssopelagic layers at a deepness of roughly 1,000 to 4,000 meters (3,280 to 13,120 feet).
2. A reference to organisms living in the steep descent of the ocean bed from the abyssal zone to the continental shelf: Jack read about a scavenger that fed on the dead whales and squid in the midnight zone, or bathypelagic zone, of the sea where light does not penetrate.

A layer of the oceanic zone lying below the "mesopelagic" zone and above the "abyssopelagic" zone, at depths generally between 1,000 and 4,000 meters (3,280 to 13,120 feet): The bathypelagic zone receives no sunlight and water pressure is considerable. The abundance and diversity of marine life decreases with depth through the bathypelagic zone and the lower zones.