a shallow lake in the NW Netherlands; formed from the S part of the Zuider Zee by the construction of the IJsselmeer Dam in 1932; salt water gradually replaced by fresh water from the IJssel River; fisheries (formerly marine fish, now esp eels). Area: (before reclamation) 3690 sq km (1425 sq miles). Estimated final area: 1243 sq km (480 sq miles)