Lake Copais

Lake Copais was a large shallow lake in Boeotia, central Greece, fed by the Cephissus river. In the Mycenaean period the people of Orchomenos drained much of it with dykes, canals and channels into natural sinkholes, one of the great engineering works of the Bronze Age. The works later failed and the lake returned, until it was finally drained in the late 19th century.