Tanganyika, Lake, a large freshwater lake in east-central Africa. It lies at an elevation of 2,530 feet (770 m) in the Great Rift Valley and borders Burundi, Tanzania, Zambia, and Zaire. Some 450 miles (720 km) long and up to 50 miles (80 km) wide, with an area of 12,700 square miles (32,900 km2), it is the world's seventh largest lake. In depth (4,823 feet [1,470 m] maximum) it is second only to Lake Baikal in Siberia.

Water from Lake Tanganyika drains westward to the Congo River by way of the Lukuga River. There is regular steamer service on the lake. The chief ports are Kigoma, Tanzania, and Kalemie, Zaire, which are also railway terminals.

Lake Tanganyika was discovered by John Speke and Sir Richard Burton in 1858. Henry M. Stanley found David Livingstone on its shores near Ujiji in 1871.