Lake Natron: Tanzania’s bright pink salty soda lake

Situated in Africa’s Great Rift Valley, Lake Natron’s bright pink waters stand out in more ways than one. In addition to its eye-catching colour, the lake is also hypersaline, meaning that it is supersaturated with salt.

Ash from the once volcanic mountains nearby has enriched the soil on the lake bed with natron, the chemical compound from which the lake gets its name. Natron consists mainly of sodium carbonate, a salt that dissolves in the water to make it strongly alkaline. This type of lake is known as a soda lake, as its water has an extremely alkaline pH of between 9 and 10.5. Acidic rain sometimes reduces this value, but wet weather is erratic in the region.

The lake’s salt crust changes colour from red to pink or orange depending on the microorganisms present.

Additional salts are also fed into the lake from nearby hot springs, and because the lake has no outlet, it is all left behind as the water evaporates. In fact, Lake Natron was originally a much larger freshwater lake, but as the hot, dry climate evaporated much of the water, it shrank and became very salty. The water is also a very warm 40 degrees Celsius (104 degrees  ahrenheit), but can sometimes reach a scolding 60 degrees Celsius (140 degrees Fahrenheit).

The lake’s distinctive colour comes from the microorganisms that thrive on the salt within, but there aren’t many other creatures that can survive these extreme conditions. Only one species of fish, the tilapia, is tough enough to live in the lake, but most other animals that venture into the water will die and become encrusted with salts when water levels drop. The natron, which was used in Egyptian mummifi cation, helps to preserve their bodies, causing eerie stone-like fi gures to occasionally  wash up onto the shore.

The wonderful wildlife of Lake Natron

Three-quarters of the world’s lesser flamingos use Lake Natron as their nesting site.