Murray River, Australia's principal river. It is about 1,600 miles (2,600 km) long, and with its tributaries, including the Darling and Murrumbidgee, forms a great river system in southeastern Australia that drains some 400,000 square miles (1,000,000 km2). The Murray begins in the Australian Alps and flows westward along 1,609 miles (2,589 km) of the boundary between New South Wales and Victoria. In South Australia it turns southward, emptying into the Indian Ocean through Lake Alexandrina. The Murray's valley is one of the most densely settled parts of Australia.

Numerous dams on the Murray and its tributaries provide hydroelectric power and water for irrigation. In the Australian Alps, tunnels divert water from southward- and eastward-flowing rivers into the Murray and Murrumbidgee basins, which are relatively dry.