Ol Doinyo Lengai

The Mountain of God, and it is erupting now

Ol Doinyo Lengai rises abruptly from the Rift floor south of Lake Natron — a point of geography travel copy frequently reverses — and stands at 2,962 metres, a figure given independently by the Smithsonian Institution’s Global Volcanism Program, by UNESCO and by the Tanzania Wildlife Management Authority. Ol Doinyo Lengai is the Maasai name, translated by both the Smithsonian and UNESCO as the Mountain of God, and the mountain is a sacred site to the communities living around it.

Two facts about it are more consequential than anything else on this page.

It is the only volcano on earth known to erupt natrocarbonatite lava — a sodium carbonate melt with almost no silica in it, which UNESCO gives as erupting at around 510 °C, roughly half the temperature of basalt. That is why it appears black in daylight rather than glowing, runs almost like water, and weathers to a pale crust that makes the cone look snow-streaked on the equator.

It has been in continuous eruption since 9 April 2017, according to the Smithsonian’s Global Volcanism Program, and was still erupting at the most recent date in that database. Activity is low-level lava effusion in the northern crater rather than anything explosive, which is why it can be climbed at all. Sources describing it as dormant, or as having last erupted in 2006 or 2008, are wrong: the previous eruption began on 16 June 2007 and ran to 9 October 2010.

Who governs it, which is not obvious

Lengai is not part of the Ngorongoro Conservation Area in the way the crater is — UNESCO places it in the vicinity of the property rather than among its features. It is inside the much larger Ngorongoro Lengai UNESCO Global Geopark, designated in 2018, and the Lake Natron side is administered by the Tanzania Wildlife Management Authority as a game controlled area.

The practical consequence is that no park authority gates the climb. There is no permit desk and no ranger, and climbs are arranged through guides in Engare Sero village at the foot of the mountain.

The climb, and why it has its own guide

The ascent is a single continuous night push on steep, loose volcanic ash, with no camps, no staged profile and nowhere to stop. It is among the hardest single nights of walking available to a traveller in Tanzania, and it is covered properly in the climbing Ol Doinyo Lengai guide rather than here.

One thing from that guide belongs on any page about this mountain. The British Geological Survey states plainly that there are no rescue measures in place on Ol Doinyo Lengai, and records one documented climber injury in which a visitor stepped on the cooled crust of a lava flow, which gave way to the molten core, and lost a leg. Anyone injured on this mountain is brought down by the people they came with.

Looking at it rather than climbing it

The mountain is a better object from below than most people expect, and it is visible from most of the Natron basin as well as from the rim of Empakaai Crater in the highlands. Its ash is also the material of the Shifting Sands dune and of the mudflow that preserved the Engare Sero footprints at its foot.

Common questions