The sundarbans is the largest forest mangrove forest of the world .It has been declared the world heritage site of the world. The sundarbans is also an attractive and tourist sport. The natural beauty of sundarbans is charming. The Sundarbans along the Bay of Bengal has evolved over the millennia through natural deposition of upstream sediments accompanied by intertidal separation. The physiographic is subjugated by deltaic formations that consist of numerous drainage lines related with surface and subaqueous levees, splays and tidal flats. There are also marginal marshes above mean tide level, tidal sandbars and islands with their network of tidal channels, subaqueous distal bars and proto-delta clays and silt sediments. The sundarbans is as known as mangrove forest and has a many various kind of trees such as Sundari ,gewa, poshour, dhundul and many other are found in this forest. Sundari and Gewa occur significantly throughout the area with alternating distribution of Dhundul and Kankra. The sundarbans is a wonderful place as a natural beauty. sundarbans fresh water are a tropical moist broadleaf forest ecoregion of Bangladesh .It represents the salty swamp forests that lie behind the sundarbans mangroves where the salinity is more prominent. The freshwater ecoregion is an area where the water is only slightly brackish and becomes quite fresh during the rainy season, when the freshwater plumes from the Ganges and the Brahmaputra rivers push the intruding salt water out and transport a deposit of buildup. The Sundarbans was everywhere intersected by river channels and creeks, some of which afforded water communication throughout the Bengal section both for steamer and for native boats. The Sundarbans is very important wintering area for refugee water birds and is an area suitable for watching and studying avifauna. The Sundarbans provides a unique ecosystem and a rich wildlife environment. The Bangladesh mangrove plant life of the Sundarbans differs greatly from other non-deltaic coastal mangrove forests and upland forests associations. nothing like the former, the Rhizophoraceae are of slight importance. Differences in vegetation have been explained in terms of freshwater and low salinity influences in the Northeast and variations in drainage and siltation. The Sundarbans has been classified as a moist tropical forest representing a whole variety of seres, comprising most important colonization on new accretions to new mature beach forests, a lot conspicuously dominated by Keora forests. In the past three principal undergrowth types have been recognized in broad link with varying degrees of water salinity, freshwater flushing and physiographic and which are represented in the wildlife sanctuaries.