Lake Natron

Lake Natron is one of East Africa's most alien landscapes — a 56 km-long highly alkaline soda lake in Tanzania's Great Rift Valley whose pH reaches 10.5, caustic enough to calcify the skin of animals that die in its waters, creating eerily preserved stone sculptures of birds and mammals along its shores. Yet this apparently hostile environment is the most important breeding site on Earth for the lesser flamingo (Phoeniconaias minor), a Near Threatened species that breeds here in concentrations of 1.5–2.5 million birds — up to 75% of the world's entire lesser flamingo population — according to the African Flamingo Conservation Database (2019). The lake's distinctive crimson and orange colouration — caused by salt-loving cyanobacteria (Spirulina platensis) and haloarchaea that thrive in the brine — photographs like something from another planet, and aerial images of Lake Natron have been circulated internationally as examples of Earth's most surreal natural phenomena. The lake is located at the foot of Ol Doinyo Lengai volcano and is frequently combined with a Lengai climb in a 2–3 day Rift Valley itinerary. Lake Natron was proposed for a soda ash extraction operation in 2007; the project was abandoned following international conservation pressure led by BirdLife International, protecting the flamingo breeding grounds indefinitely.