The Sundarbans-the largest continuous blackofmangrove forest in the world –covers in area of 5770sq.km of land and water. It is a part of world's largest delta, which has been formed form sediments deposited by the great rivers Ganges and Bhamhaputra that converge on to the Bengal basin. The western part of the forest lies India and the rest [about 60%] in Bangladesh . River channels and tidal creeks, varying, in width from just a few meters to five kilometers in some places All parts of the Sundarbans forest are subject 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-Feb] is mild and dry. During January temperature can fall as low as 4 deg c.

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. The two dominant mangroves are Sundori and Gewa
[ Excoecaria agallocha]