A network of estuaries, tidal rivers, and creeks intersected by numerous channels, it encloses flat, marshy islands covered with dense forests.

The name Sundarbans is perhaps derived from the term meaning "forest of sundari, a reference to the large mangrove tree that provides valuable fuel. Along the coast the forest passes into a mangrove swamp; the southern region, with numerous wild animals and Crocodile- infested estuaries, is virtually uninhabited. It is one of the last preserves of the Bengal tiger and the site of a tiger preservation project.