Ol Doinyo Lengai rises to roughly 2,960 metres above the Rift Valley floor near Lake Natron. In Maa its name means Mountain of God, and it holds real religious significance for the Maasai, who make pilgrimages to it.
Geologically it is unique. It is the only active volcano on earth erupting natrocarbonatite lava — a carbonate rather than silicate melt, which erupts at around 500°C rather than the 1,100°C typical of basalt. It is so cool that it appears black in daylight rather than glowing, and it weathers to white within hours of exposure, giving the summit its distinctive snow-like appearance.
The climb is demanding: steep, loose ash and rock, usually started around midnight to reach the summit at sunrise before the heat becomes punishing. Guides are mandatory and arranged through the Maasai community at Engare Sero.