Lake Kivu is one of the African Great Lakes. It lies on the border between the Democratic Republic of the Congo and Rwanda, and is in the Albertine Rift, the western branch of the East African Rift. Lake Kivu empties into the Ruzizi River, which flows southwards into Lake Tanganyika
Lake Kivu is approximately 90 km (56 mi) long and 50 km (31 mi) at its widest. Its irregular shape makes measuring its precise surface area difficult; it has been estimated to cover a total surface area of some 2,700 km2 (1,040 sq mi). The surface of the lake sits at a height of 1,460 metres (4,790 ft) above sea level.The lake has a maximum depth of 475 m (1,558 ft) and a mean depth of 220 m (722 ft), making it the world's eighteenth deepest lake by maximum depth, and the ninth deepest by mean depth
Some 1,370 km2 or 58 percent of the lake's waters lie within DRC borders.
The lake bed sits upon a rift valley that is slowly being pulled apart, causing volcanic activity in the area.
The world's tenth-largest island on a lake, Idjwi, lies in Lake Kivu, within the boundaries of Virunga National Park. Settlements on the lake's shore include Bukavu, Kabare, Kalehe, Sake and Goma in Congo, and Gisenyi, Kibuye, and Cyangugu in Rwanda
Lake Kivu is a fresh water lake and, along with Cameroonian Lake Nyos and Lake Monoun, is one of three that are known to undergo limnic eruptions. Around the lake, geologists found evidence of massive biological extinctions about every thousand years, presumably caused by outgassing events. The trigger for lake overturns is unknown in Lake Kivu's case, but volcanic activity is suspected. The gaseous chemical composition of exploding lakes is unique to each lake, in Lake Kivu's case, methane and carbon dioxide due to lake water interaction with a volcano