Which lake is the largest natural freshwater lake in Australia?

Lake Alexandrina is generally recognised as Australia’s largest natural freshwater lake. It lies in South Australia’s Lower Lakes system, about 100 kilometres southeast of Adelaide, and covers roughly 649 square kilometres.

The lake receives water mainly from the River Murray, along with the Bremer, Angas and Finniss rivers. It adjoins smaller Lake Albert and connects toward the sea through the Murray Mouth. Together, the Lower Lakes form a major wetland at the downstream end of Australia’s largest river system.

The word “freshwater” needs some context: before modern controls, seawater could periodically move inland through the Murray Mouth, especially during low river flow. Barrages built across the channels in the 1930s and 1940s helped maintain freshwater conditions in the lakes. Lake Alexandrina is also distinct from Lake Eyre, which is Australia’s largest lake by area when filled but is usually saline and often dry.