Ol Doinyo Lengai is an active volcano located in Arusha Region, Tanzania and is part of the volcanic system of the East African Rift. It is located in the eastern Rift Valley, or Gregory Rift, south of both Lake Natron and Kenya. It is unique among active volcanoes in that it produces natrocarbonatite lava, a unique occurrence of volcanic carbonatite. Further, the temperature of its lava as it emerges is only around 510 °C (950 °F). A few older extinct carbonatite volcanoes are located nearby, including Homa Mountain.
The volcano has immense ecological, geological and cultural value. The Engaresero village located on the Western shores of Lake Natron, close to Ol Doinyo Lengai, has been chosen by the government of Tanzania to exemplify the Maasai pastoral system given its singularity, integrity, high diversity of habitats and biodiversity. The community has demonstrated a strong resilience in facing threats to their systems, and has maintained associated social and cultural institutions, which ensure its sustainability under prevailing environmental conditions.