The Bay of Bengal is the northeastern part of the Indian Ocean, bounded on the west and northwest by India, on the north by Bangladesh, and on the east by Myanmar and the Andaman and Nicobar Islands of India. Its southern limit is a line between Sangaman Kanda, Sri Lanka, and the north westernmost point of Sumatra, Indonesia. It is the largest water region called a bay in the world. There are countries dependent on the Bay of Bengal in South Asia and Southeast Asia. During the existence of British India, it was named as the Bay of Bengal after the historic Bengal region. At the time, the Port of Kolkata served as the gateway to the Crown rule in India. Cox's Bazar, the longest sea beach in the world and Sundarbans, the largest mangrove forest and the natural habitat of the Bengal tiger, are located along the bay.
The Bay of Bengal occupies an area of 2,600,000 square kilometres (1,000,000 sq mi). A number of large rivers flow into the Bay of Bengal: the Ganges–Hooghly, the Padma, the Brahmaputra–Jamuna, the Barak–Surma–Meghna, the Irrawaddy, the Godavari, the Mahanadi, the Brahmani, the Baitarani, the Krishna and the Kaveri.
Important ports include Krishnapatnam, Chennai, Ennore, Chittagong, Colombo, Kolkata-Haldia, Mongla, Paradip, Port Blair, Matarbari, Thoothukudi, Visakhapatnam and Dhamra. Among the smaller ports are Gopalpur Port, Kakinada and Payra.
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.
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 wrasse 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.
The Great Nicobar Biosphere Reserve provides sanctuary to many animals some of which include the saltwater crocodile (Crocodylus porosus), giant leatherback sea turtle (Dermochelys coriacea), and Malayan box turtle (Cuora amboinensis kamaroma) to name a few.
Another endangered species royal Bengal tiger is supported by Sundarbans a large estuarine delta that holds a mangrove area in the Ganges River Delta.