Which lake is the largest lake in Australia when it contains water?

Lake Eyre is the largest lake in Australia when it contains water.

Officially called Kati Thanda–Lake Eyre, it is an endorheic salt lake in South Australia’s arid interior. It lies in the lowest part of the Lake Eyre Basin, about 15 metres below sea level. Most of the time, the lake is a dry salt flat, but exceptional rain in its vast catchment can send water toward the basin and temporarily transform it.

The lake has two main sections, Lake Eyre North and Lake Eyre South, joined by the narrow Warburton Creek channel. Floodwaters can attract large numbers of waterbirds and support bursts of aquatic life.

It is often confused with Lake Torrens, another large salt lake in South Australia. Lake Eyre is named after explorer Edward John Eyre, who first saw it in 1840.