Lake Tanganyika
Lake Tanganyika is not the largest of the Great Lakes in surface area - Lake Victoria is the largest with 68,800 km2 (26,600 sq mi) - but has the greatest volume. It is the world's second-largest freshwater lake by volume and depth. The volumes of the lakes in the question are: Tanganyika 18,900 km3 (4,500 cu mi); Malawi 7,725 km3 (1,853 cu mi); Victoria 2,700 km3 (650 cu mi); Kivu 569 km3 (137 cu mi). The other two lakes included as Great Lakes, Lake Turkana and Lake Albert, are 204 km3 (49 cu mi) and 132 km3 (32 cu mi) respectively.