Urmia, Lake (Persian Orumìyeh Daryacheh-ye), shallow lake in northwestern Iran, west of the Caspian Sea. It is about 145 km (about 90 mi) long, with an average breadth of 48 km (about 30 mi), and occupies part of a level basin enclosed by mountains and lying at an altitude of more than 1200 m (3937 ft). The lake is fed by radial streams of considerable size, but it has no outlet. It is consequently too salty to nourish any life with the exception of certain crustaceans. The lake has been shrinking for years, exposing wide tracts of slime.