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Australia's largest lake and lowest point, a normally dry salt pan in South Australia that fills completely only about twice a century.
Kati Thanda-Lake Eyre is a vast salt lake in the Far North of South Australia, roughly 700 km north of Adelaide, and is both the largest lake in Australia and the continent's lowest natural point at about 15 metres below sea level. It has two connected parts - Lake Eyre North, about 144 km by 65 km, and the smaller Lake Eyre South, about 65 km by 24 km - covering close to 9,500 sq km when full. For most years it is not a lake at all but a glaring white salt crust, because it is the terminal sink of an endorheic basin with no outlet to the sea. It carries a dual name adopted in December 2012: Kati Thanda is the name used by the Arabana people, the traditional owners, and Lake Eyre commemorates the explorer Edward John Eyre, the first European to sight it in 1840.
Type: PhenomenonAustralia's largest lake by area when full - about 9,500 sq km - and the continent's lowest natural point at roughly 15 metres below sea level.
Endorheic, or internally drained: the Lake Eyre Basin has no outlet to the ocean, so every drop that enters either evaporates or seeps away.
The Lake Eyre Basin covers about 1.2 million sq km - roughly one-sixth of Australia - and spans South Australia, Queensland, the Northern Territory and New South Wales.
Fed mainly by the Warburton River, which collects flows from the Diamantina and Georgina rivers and from Cooper Creek. Monsoon rain falling in Queensland can take weeks to months to reach the lake.
Normally a dry salt pan; a complete filling has been recorded only about three times in roughly 160 years - 1950, 1974 and 1984 - with the 1974 event the deepest at around 6 metres.
Minor fillings of about 1.5 metres occur far more often, roughly every three years, and a full lake takes about two years to evaporate away.
Protected as Kati Thanda-Lake Eyre National Park, gazetted in 1985 and covering about 13,488 sq km.
When it floods it becomes a temporary inland sea - brine shrimp hatch, fish are carried down the channels and enormous colonies of waterbirds arrive to breed.
Frequency: A regular in world-geography lake questions across UPSC Prelims, SSC and Railway papers, and a recurring current-affairs item during the rare filling years such as 2025 and 2026.
The lake's filling is a slow relay across a continent, which is why a flood in Queensland shows up months later as water in South Australia.
Step 1: Monsoonal rain, often driven by a tropical low or an ex-cyclone, falls over inland Queensland and the Northern Territory - hundreds of kilometres from the lake.
Step 2: The runoff enters the channel country - the Georgina and Diamantina rivers and Cooper Creek - which spread into broad, shallow braided channels rather than deep single beds.
Step 3: The water creeps south at walking pace, losing much of its volume to evaporation and soaking into the floodplain along the way.
Step 4: What survives reaches the Warburton River and empties into Lake Eyre North, dissolving the salt crust and turning the pan into a shallow inland sea.
Step 5: With no outlet, the water can only evaporate. Over about two years the lake shrinks, the salinity rises, and the salt crust reforms.
Far North, South Australia, about 700 km north of Adelaide
About 9,500 sq km
About 15 m below sea level - the lowest natural point in Australia
About 144 km x 65 km
About 65 km x 24 km
About 1.2 million sq km, roughly one-sixth of Australia
Endorheic - no outlet to the sea
Warburton River (fed by the Diamantina, the Georgina and Cooper Creek)
1950, 1974, 1984 - about three times in 160 years
Kati Thanda-Lake Eyre National Park, gazetted 1985, about 13,488 sq km
December 2012 - Kati Thanda from the Arabana language
Kati Thanda-Lake Eyre is the textbook case of an ephemeral lake in an arid, internally drained basin - the clearest illustration of why endorheic drainage produces salt rather than freshwater. The rivers that feed it form one of the world's last large unregulated dryland river systems, unusual in an age when almost every major river is dammed or diverted, and their protection is managed cooperatively across the four states and territories the basin spans. Ecologically the lake matters precisely because it is unreliable: when it fills, dormant brine shrimp eggs hatch, fish move down the flooded channels, and pelicans and other waterbirds arrive in enormous numbers to breed, then disperse as the water goes. The 2025 and 2026 filling events - the second following record inland rainfall, with water covering an estimated 70 to 80 per cent of the lake and levels the highest in decades - drew worldwide attention and put the lake back into current affairs.
Kati Thanda-Lake Eyre - South Australia, about 700 km north of Adelaide.
Australia's largest lake; lowest natural point in Australia, about 15 m below sea level.
Ephemeral salt lake in an endorheic basin - no outlet to the sea.
Area about 9,500 sq km when full; two parts, Lake Eyre North and Lake Eyre South.
Lake Eyre Basin: about 1.2 million sq km, roughly one-sixth of Australia.
Fed by the Warburton, which collects the Diamantina, the Georgina and Cooper Creek.
Complete fills recorded in 1950, 1974 and 1984; 1974 was the deepest at about 6 m.
Dual name adopted December 2012 - Kati Thanda is the Arabana name; Eyre sighted it in 1840.
Kati Thanda-Lake Eyre National Park gazetted 1985, about 13,488 sq km.
Major filling events in 2025 and 2026 - about 70-80% of the surface covered in 2026.
It lies in the Far North of South Australia, roughly 700 km north of Adelaide, and is the terminal sink of the Lake Eyre Basin.
It sits in one of Australia's most arid regions and has no outlet to the sea. Floodwater must travel hundreds of kilometres from Queensland, and most of it evaporates or soaks away before arriving, so the lake bed is normally a salt crust.
Yes. At about 15 metres below sea level, Kati Thanda-Lake Eyre is the lowest natural point on the Australian continent.
Very rarely - about twice a century. Complete fillings were recorded in 1950, 1974 and 1984, with 1974 the deepest at around 6 metres. Smaller fillings of about 1.5 metres occur roughly every three years.
Kati Thanda is the name for the lake in the language of the Arabana people, its traditional owners. The dual name Kati Thanda-Lake Eyre was officially adopted in December 2012.
The largest lake lying entirely within Canada, straddling the Arctic Circle in the Northwest Territories and draining into the Mackenzie River.
The largest freshwater lake in the world by surface area, the deepest and northernmost of North America's Great Lakes, shared by Canada and the United States.