Is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of the East African Rift. The lake is fed by the Southern Ewaso Ng’iro River and also by mineral-rich hot springs. It is quite shallow, less than three metres (9.8 ft) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving behind a mixture of salts and minerals called natron. The surrounding country is dry and receives irregular seasonal rainfall. The lake falls within the Lake Natron Basin Wetlands of International Importance Ramsar Site. Temperatures in the lake can reach 60 °C (140 °F), and depending on rainfall, the alkalinity can reach a pH of 9 to 10.5 (almost as alkaline as ammonia).
The high temperature (up to 60°C) and the high and very variable salt content of the lake does not support wildlife. However it is an important habitat for flamingos and is home to endemic algae, invertebrates and round the margins even fish that can survive in the slightly less salty water.
The lake is the only regular breeding area in East Africa for the 2.5 million Lesser Flamingoes, whose status of “near threatened” is a consequence of their dependence on the single breeding location. As salinity increases, so do the number of cyanobacteria, and the lake can support more nests. These flamingoes, the single large flock in East Africa, gather along saline lakes in the region, where they feed on Spirulina (a blue-green algae with red pigments). Lake Natron is a safe breeding location because its caustic environment is a barrier against predators trying to reach their nests on seasonally-forming evaporite islands. Greater Flamingo also breed on the mud flats.