- Lake Tanganyika (/ˌtæŋɡənˈjiːkə, -ɡæn-/ TANG-gən-YEE-kə, -gan-; Kirundi: Ikiyaga ca Tanganyika) is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second deepest, in all cases after Lake Baikal in Siberia. It is the world’s longest freshwater lake. The lake is shared among four countries—Tanzania, the Democratic Republic of the Congo (the DRC), Burundi, and [Zambia](/en.wikipedia.org/wiki/Zambia/—with Tanzania (46%) and the DRC (40%) possessing the majority of the lake. It drains into the Congo River system and ultimately into the Atlantic Ocean.