Fens are a low-lying region of land in eastern England, extending west and south of The Wash as far as Cambridge. They include parts of the counties of Lincolnshire, Norfolk, Cambridgeshire, and Suffolk. The Fens (also called the Fen Country) form the drainage basin of the Rivers Great Ouse, Nene, Welland, and Witham. They cover about 500,000 acres (200,000 hectares).