Which of swampland covers 1398800 areas?

Sundarbans is the largest single block of tidal halophytic mangrove forest in the world, found on the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal. It spans from the Hooghly River in West Bengal, India, to the Baleswar River in Bangladesh. It covers approximately 10,000 square kilometres.