Lake Alexandrina: Estuarine lagoon in South Australia, forming part of the Murray River mouth

The lake covers an area of 56,000 ha (138,379 acres). The Murray River flows into the north of the lake near Wellington. Water from the lake enters the sea through an opening into Encounter Bay. In 1940 a number of walls were built to stop sea water from flowing back into the lake which would stop the lake from being salty. These walls separate the lake from the Murray River's estuary lagoon, called the Coorong.

Lake Alexandrina
Lake Alexandrina is the largest of the Lower Lakes
Location	South Australia
Coordinates	35°25′S 139°07′E / 35.417°S 139.117°E / -35.417; 139.117
Primary inflows	Murray, Bremer, Angas, and Finniss Rivers
Primary outflows	Murray Mouth
Catchment area	1,061,469 square kilometres (409,835 sq mi)
Basin countries	Australia
Surface area	64,900 hectares (251 sq mi)
Average depth	2.8 metres (9.2 ft)
Max. depth	6 metres (20 ft)
Water volume	1,610 gigalitres (0.39 cu mi)
Surface elevation	0.75 metres (2.5 ft)
Settlements	Milang

Lake Alexandrina and the Coorong are a Wetland of International Importance under the Ramsar Convention on Wetlands. Many bird species live around the lake including Curlew Sandpiper, Banded Stilt, Red-capped Plover, Masked Lapwing, Redkneed Dotterel, Black Swan, Cape Barren Goose, Musk Duck, Straw-necked Ibis, Royal Spoonbill, Rufus Night Heron and the Australian Pelican. Rare species such as the Orange Bellied Parrot and the Southern Mount Lofty Ranges Emu Wren have been seen. The large Murray Cod can also be found in the lake.

The Ngarrindjeri, an Indigenous Australian people, have lived around the lake and the wetlands for thousands of years. The first Europens to find the lake were people hunting seals along the south east coast of Australia in 1828. In 1830, the explorer Charles Sturt reached the lake by boat after a long journey down the Murrumbidgee, the Darling and the Murray Rivers. Sturt named the lake after Princess Alexandrina, who later became Queen Victoria.

Lake Alexandina became important during the 1870s when paddle steamers began to use the Murray River system to carry goods around New South Wales, Victoria, and South Australia. The town of Milang, on the lake, became an important port. It is now popular as a place for holidays with activities including sailing, power boating, fishing and swimming.