Ol Doinyo Lengai is an active volcano in Tanzania. It consists of a volcanic cone with two craters, the northern of which has erupted during historical time. The Ol Doinyo Lengai, is the only volcano in the world to emit natrocarbonatite lava — dark gray, relatively cool (about 950 degrees Fahrenheit) and fast-flowing.
The Empakaai Crater, is nearly four miles across and one of the few in the region filled with a lake;