Turkana, Lake, c.2,500 sq mi (6,475 sq km), NW Kenya and SW Ethiopia, E Africa, in the Great Rift Valley; alt. 1,230 ft (375 m). Surrounded by desolate, volcanic mountains, the 170-mi- (274-km-) long lake is the focus of interior drainage and has no outlet; it is becoming increasingly saline. Fishing and tourism are important to local economy. Nearby is Kanapoi, an archaeological site with 4.1-million-year-old australopithecine fossils. It was formerly known as Lake Rudolf.