The Sundarban - the largest continuous block of mangrove forest in the world. It is a part of the world's largest delta. About one third of the total area of this forest is covered by river channels and tidal creeks, varying in width from just a few meters to 5 kilometers in some places! All parts of the Sundarban forest are subject to tidal inundation during spring tides. The Bangladesh part of the forest is dominated by a high mangrove forest cover. The climate is mainly tropical maritime with lots of rain, most of which falls during the monsoon. The monsoon season (May – October) is hot and humid, while winter (October – February) is mild and dry. The entire National Park area is covered by mangrove forest. There are small patches of brackish marshes on emerging islands and riverbanks, and sandy areas with grass and low shrubs on some of the outer islands.
Sundarban is home to many different species of birds, mammals, insects, reptiles and fishes. Over 120 species of fish and over 270 species of birds have been recorded in the Sundarban.
About 32 species of mammal are still found in this forest. Among these are Rhesus Macaques, Clawless Otters, Leopard Cats, Fishing Cats and Spotted Deer. The entire Sundarban Forest comprises the largest remaining tract of habitat for the Royal Bengal Tiger (Panthera tigris).