The Sundarban is the largest mangrove forest in the world.

The Sundarban  is the largest halophytic mangrove forest in the world.

The forest lies in the vast delta on the Bay of Bengal formed by the super confluence of the Padma, Brahmaputra and Meghna rivers across Saiyan southern Bangladesh. The forest covers 10,000 sq.km. of which about 6,000 are in Bangladesh. It became inscribed as a UNESCO world heritage suite in 1997. The Sundarbans is estimated to be about 4,110 km², of which about 1,700 km² is occupied by waterbodies in the forms of river, canals and creeks of width varying from a few meters to several kilometers.

The Sundarbans is intersected by a complex network of tidal waterways, mudflats and small islands of salt-tolerant mangrove forests. The interconnected network of waterways makes almost every corner of the forest accessible by boat. The area is known for the eponymous Royal Bengal Tiger (Panthera tigris tigris), as well as numerous fauna including species of birds, spotted deer, crocodiles and snakes. The fertile soils of the delta have been subject to intensive human use for centuries, and the ecoregion has been mostly converted to intensive agriculture, with few enclaves of forest remaining. The remaining forests, pain together with the Sundarbans mangroves, are important habitat for the endangered tiger. The Sundarbans has also been enlisted among the finalists in the New7Wonders of Nature.

Fauna:

The Sundarbans provides a unique ecosystem and a rich wildlife habitat. According to the 2011 tiger census, the Sundarbans have about 270 tigers. Although previous rough estimates had suggested much higher figures close to 300, the 2011 census provided the first ever scientific estimate of tigers from the area[19][20] Tiger attacks are frequent in the Sundarbans. Between 100 and 250 people are killed per year.

Chital deer are widely seen in southern parts of Sundarban

There is much more wildlife here than just the endangered Royal Bengal Tiger (Panthera tigris tigris). Most importantly, mangroves are a transition from the marine to freshwater and terrestrial systems, and provide critical habitat for numerous species of small fish, crabs, fidler crabs, hermit crabs, shrimps and other crustaceans that adapt to feed and shelter, and reproduce among the tangled mass of roots, known as pneumatophores, which grow upward from the anaerobic mud to get the supply of oxygen. Fishing Cats, Macaques, wild boars, Common Grey Mongooses, Foxes, Jungle Cats, Flying Foxes, Pangolins, and spotted deer are also found in abundance in the Sundarbans.

Avifauna:

Blue-eared Kingfisher sighted in the Sundarbans

The forest is rich in bird life too with 170 species including the endemic Brown-winged Kingfishers (Pelargopsis amauroptera) and the globally threatened Lesser Adjutants (Leptoptilos javanicus) and Masked Finfoots (Heliopais personata) and birds of prey such as the ospreys (Pandion haliaetus), White-bellied Sea Eagles (Haliaeetus leucogaster) and Grey-headed Fish-eagles (Ichthyophaga ichthyaetus). The Sundarbans was designated a Ramsar site on May 21, 1992.[28] Some of the more popular birds found in this region are Open Billed Storks, White Ibis, Water Hens, Coots, Pheasant-tailed Jacanas, Pariah Kites, Brahminy Kites, Marsh Harriers, Swamp Partridges, Red Junglefowls, Spotted Doves, Common Mynahs, Jungle Crows, Jungle Babblers, Cotton Teals, Herring Gulls, Caspian Terns, Gray Herons, Brahminy Ducks, Spot-billed Pelicans, great Egrets, Night Herons, Common Snipes, Wood Sandpipers, Green Pigeons, Rose Ringed Parakeets, Paradise Flycatchers, Cormorants, Fishing Eagles, White-bellied Sea Eagles, Seagulls, Common Kingfishers, Peregrine falcons, Woodpeckers, Whimprels, Black-tailed Godwits, Little Stints, Eastern Knots, Curlews, Golden Plovers, Pintails, White Eyed Pochards and Whistling Teals.

 Reptiles:

A crocodile at Sundarbans

The Sundarbans National Park houses an excellent number of reptiles as well. Some of the common ones are Olive Ridley turtles, sea snakes, Dog Faced Water Snakes, Green Turtles, Estuarine Crocodiles, Chameleons, King Cobras, Salvator Lizards, Hard Shelled Batgun Terrapins, Russels Vipers, Mouse Ghekos, Monitor Lizards, Curviers, Hawks Bill Turtles, Pythons, Common Kraits, Chequered Killbacks and rat Snakes. The river terrapin (Batagur baska), Indian flap-shelled turtles (Lissemys punctata), peacock soft-shelled turtles (Trionyx hurum), yellow monitors (Varanus flavescens), water monitors (Varanus salvator), and Indian pythons (Python molurus).