Lake Natron and Ol Doinyo Lengai

Overview

Lake Natron sits in the hottest, lowest part of the Tanzanian Rift, a shallow soda lake whose water can reach 60 degrees and a pH close to ammonia. Almost nothing lives in it, which is precisely why it matters: the caustic water keeps predators away, and virtually the entire East African population of lesser flamingo - well over two million birds - breeds here and nowhere else. Seen from the air the lake turns deep red from the salt-loving microorganisms that also feed the flamingos. Above it stands Ol Doinyo Lengai, the Maasai's Mountain of God, the only active volcano on earth that erupts natrocarbonatite lava - cool enough to run black and turn white as it weathers. The climb is a brutal overnight scramble of about 1,700 metres on loose ash, usually starting around midnight to reach the crater at sunrise. The area is Maasai land, dry, hot and sparsely settled, with waterfalls in the Engare Sero gorge and hominin footprints preserved in volcanic ash nearby.