Mount Ol Doinyo Lengai

Mount Ol Doinyo Lengai is the holy mountain of the Maasai, in the Arusha region of Tanzania.

It lies 240 kilometers northwest of Arusha town, along the western wall of the Great Rift Valley, above Lake Natron near the border with Kenya.

The Maasai people call Ol Doinyo Lengai the “Mountain of God”, and it's the only active volcano in Tanzania. It rises from the floor of the Great Rift Valley to a height of 2890m. It's the only active volcano in the world that erupts carbonatite lava. This kind of lava is very rare. It's only about 500°C, roughly half the temperature of normal basalt lava, and it flows almost as easily as water.

You can climb the mountain in 6 hours, with great views of the Great Rift Valley and the volcanic landscape of the Ngorongoro Highlands as you reach the summit. It's a tough climb that starts before first light. Remember that this is an active volcano: the mountain is closed to climbers when it's erupting.

Scientists see it as a fascinating place for geochemistry, and it's a hard physical climb. The slope is steep, which makes both the climb and the descent difficult, and the daytime heat is brutal. The best time to climb is at night, when it's cooler. That way you reach the summit for sunrise and get back down before the heat sets in.