Murtnaghurt Lagoon, also known as Murtnaghurt Swamp or Lake Murtnaghurt, is a shallow, ephemeral wetland west of the town of Barwon Heads on the southern coast of the Bellarine Peninsula in Victoria, Australia. It comprises two enclosed depressions, elongated west-east and separated by a low ridge. The wetland is about 2 kilometres (1.2 mi) in length, and up to 600 metres (2,000 ft) wide, with 4.5 kilometres (2.8 mi) of shoreline enclosing an area of 81 hectares (200 acres).