[youtube=http://www.youtube.com/v/cAkcRQdbPV4?f=user_uploads&app=youtube_gdata] Formed by the union of three mighty rivers ‘Ganga, Brahmaputra and Meghna’ the extensive Sundarbans delta covers an area of 38500 sq km, with a major portion of it spreading into Bangladesh. The Indian part of the delta is home to the Sunderbans National Park, declared a UNESCO World Heritage Site in 1987.