<P> A zone 50 m wide extending from the island of Ceylon and the Coromandel coast to the head of the bay, and thence southwards through a strip embracing the Andaman and Nicobar islands, is bounded by the 100 fathom line of sea bottom; some 50 m. beyond this lies the 500 - fathom limit . Opposite the mouth of the Ganges, however, the intervals between these depths are very much extended by deltaic influence . </P> <P> Swatch of No Ground is a 14 km - wide deep sea canyon of the Bay of Bengal . The deepest recorded area of this valley is about 1340 m . The submarine canyon is part of the Bengal Fan, the largest submarine fan in the world . </P> <P> The Bay of Bengal is full of biological diversity, diverging amongst coral reefs, estuaries, fish spawning and nursery areas, and mangroves . The Bay of Bengal is one of the World's 64 largest marine ecosystems . </P> <P> Kerilia jerdonii is a sea snake of the Bay of Bengal . Glory of Bengal cone (Conus bengalensis) is just one of the seashells which can be photographed along beaches of the Bay of Bengal . An endangered species, the olive ridley sea turtle can survive because of the nesting grounds made available at the Gahirmatha Marine Wildlife Sanctuary, Gahirmatha Beach, Odisha, India . Marlin, barracuda, skipjack tuna, (Katsuwonus pelamis), yellowfin tuna, Indo - Pacific humpbacked dolphin (Sousa chinensis), and Bryde's whale (Balaenoptera edeni) are a few of the marine animals . Bay of Bengal hogfish (Bodianus neilli) is a type of wrass which live in turbid lagoon reefs or shallow coastal reefs . Schools of dolphins can be seen, whether they are the bottle nose dolphin (Tursiops truncatus), pantropical spotted dolphin (Stenella attenuata) or the spinner dolphin (Stenella longirostris). Tuna and dolphins usually reside in the same waters . In shallower and warmer coastal waters the Irrawaddy dolphins (Orcaella brevirostris) can be found . </P>

The deepest depression in the world holds what body of water what countries does it touch