Ol Doinyo Lengai, Tanzania [-2.7734503796, 35.91519798] What's in the photo? The lava-stained slopes and ash cone of a highly active volcano Who took the photo? The explosive volcano produces a rare type of lava that is unusually cool, uniquely colored and the fastest-flowing on Earth. Ol Doinyo Lengai is one of Africa's most active volcanoes; it has been erupting on and off for the past 15,000 years. For most of the past century, Ol Doinyo Lengai's summit consisted of a bowl-like depression that gradually filled with lava.