Lake Eyre

Kati Thanda–Lake Eyre is a massive endorheic lake in South Australia.

An endorheic lake is a body of water that does not flow into an ocean. Instead, it drains into an internal basin. This lake sits about 700 km north of Adelaide. It is located in the east-central part of the Far North region. The lake is the central point of the Lake Eyre Basin. This basin is one of the largest endorheic systems on Earth. It covers about 15 percent of the Australian landmass. This system includes parts of South Australia, the Northern Territory, Queensland, and New South Wales.

The geography of the lake is defined by its extreme depth and low elevation. It contains the lowest natural point in Australia. This point is approximately 15 meters below sea level. The deepest areas are found in Belt Bay and the Madigan Gulf. The lake is divided into two main sections. These sections are joined by the Goyder Channel. The first section is Lake Eyre North. It is 150 km long and 100 km wide. The second section is Lake Eyre South. It measures 100 km long and 50 km wide.

The lake's appearance changes based on the cycle of flooding and evaporation. Most of the time, the lake is empty. It consists of a vast, white salt crust.

This crust can be up to 2 meters thick in the southern sub-basins. When heavy monsoon rains occur in the Channel Country, water flows toward the lake. This water travels through rivers like the Warburton River. A flood can fill the lake to its capacity. Between 1860 and 2025, the lake has only been completely full three times. When full, it covers over 9,000 square kilometers. This makes it the largest lake in Australia during those rare times.

Salinity, or saltiness, is a major feature of the lake's water. When the lake first fills, the water is almost fresh. Native fish like bony bream and golden perch can survive in these waters. However, the water becomes saltier as it evaporates. As the water levels drop, the salinity increases until it reaches the same level as seawater. If it evaporates further, the water becomes hypersaline. This high salt content can cause massive fish kills. The water can even turn a bright pink color. This happens because of an alga called Dunaliella salina, which contains a pink beta-carotene pigment.

The history of the lake involves both Indigenous and European records. The Arabana people hold native title over most of the lake. It holds deep spiritual significance in their Dreaming stories. The Dieri people hold native title over the eastern portion. European explorer Edward John Eyre first saw the lake in 1840. It was named after him for many years. In December 2012, the name was officially changed to Kati Thanda–Lake Eyre. This followed a policy of dual naming to honor the Aboriginal language. Early explorers described the dry lake as a place of extreme sterility. Geologists later noted it was once the living heart of Australia.

Because the salt flats are so flat, they have been used for speed. In the 1960s, people attempted to set land speed records there. Donald Campbell used a vehicle called the Bluebird-Proteus CN7. On July 17, 1964, he set a record for four-wheeled vehicles. He reached a speed of 403.10 mph.

The salt flats provided a surface similar to the Bonneville Salt Flats in the United States.

Kati Thanda–Lake Eyre is also a vital site for wildlife. It is one of the most important locations for waterbirds in Australia. When the lake fills, birds migrate from very far away. Some birds fly all the way from Papua New Guinea. During the 1989–1990 flood, about 200,000 pelicans visited the lake. This number represented 80 percent of the total pelican population in Australia.

These birds come to feast on the fish brought in by the floods. The entire ecosystem relies on the rare and powerful arrival of water.