The Wash is a square bay and estuary at the north-west corner of East Anglia on the East coast of England, where Norfolk meets Lincolnshire, and both border the North Sea. One of the broadest estuaries in the United Kingdom, it is fed by the rivers Witham, Welland, Nene and Great Ouse. It is a 62,046-hectare (153,320-acre) biological Site of Special Scientific Interest. It is also a Nature Conservation Review site, Grade I, a National Nature Reserve, a Ramsar site, a Special Area of Conservation and a Special Protection Area. It is in the Norfolk Coast Area of Outstanding Natural Beauty and part of it is the Snettisham Royal Society for the Protection of Birds nature reserve.