Lake Kivu

Lake Kivu lies high in the western branch of the East African Rift, enclosed by steep shores and overlooked by the Virunga volcanoes. Its irregular waters contain many islands, the largest of which is Idjwi. Volcanic activity blocked an earlier northward drainage, and the lake now empties south through the Ruzizi River towards Lake Tanganyika. Deep beneath its fresh surface waters lie dissolved methane and carbon dioxide, held in layers that do not readily mix with the water above.