The document discusses the Sundarbans, a mangrove forest located in the delta region between India and Bangladesh. It describes the two main ecoregions as the freshwater swamp forest and the brackish swamp forest dominated by Sundari mangroves. The Sundarbans contain a rich diversity of flora and fauna, including 245 plant species, 270 tigers, and 170 bird species. However, populations of some plants and animals have declined in recent decades due to threats like loss of habitat.