An endorheic basin (; also spelled endoreic basin or endorreic basin) is a drainage basin that normally retains water and allows no outflow to other external bodies of water, such as rivers or oceans, but drainage converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation. They are also called closed or terminal basins, internal drainage systems, or simply basins. Endorheic regions contrast with exorheic regions. Endorheic water bodies include some of the largest lakes in the world, such as the Caspian Sea, the world's largest inland body of water.Basins with subsurface outflows which eventually lead to the ocean are generally not considered endorheic; they are cryptorheic.Endorheic basins constitute local base levels, defining a limit of erosion and deposition processes of nearby areas. Etymology The term was borrowed from French endor(rh)éisme, coined from the combining form endo- (from Ancient Greek: ἔνδον éndon 'within') and ...