Vast areas of tropical swamp and deltas are found in the Indomalayan ecozone, where great rivers, fed by the snow and glaciers of the mighty Himalayas, wander across the lowlands and empty into the Indian Ocean. Mangrove swamps develop at the ocean's edge on the mud banks built up by debris deposited by the rivers. The mangrove swamp usually blends into the tropical forest on the drier land, and many of the tree creatures that live here are the same as those further inland.