Lake Tanganyika is situated within the Albertine Rift, the western branch of the East African Rift and is confined by the mountainous walls of the valley. It is the largest rift valley lake in Africa and the second largest lake by volume in the world. It is the deepest lake in Africa and holds the greatest volume of fresh water.
Two main rivers flow into the lake as well as numerous smaller rivers and streams. There is one major outflow, the Lukuga River which empties into the Congo River drainage.
The major river flowing into the lake is the Ruzizi River which enters the north of the lake from Lake Kivu. The Malagarasi River which is Tanzania’s second largest river enters the east side of Lake Tanganyika. The Malagarasi is older than Lake Tanganyika and before the lake was formed, directly drained into the Congo River.
The lake has a complex history of changing flow patterns, due to its high altitude, great depth, slow rate of refill and mountainous location in a turbulently volcanic area that has undergone climate changes. Apparently it has rarely in the past had an outflow to the sea. The lake’s connection to the sea is dependent on a high water level allowing water to overflow out of the lake through the Lukunga into the Congo.
Due to the lake’s tropical location, it has a high rate of evaporation. Thus it depends on a high inflow through the Ruzizi out of Lake Kivu to keep the lake high enough to overflow. The lake may also have at times had different inflows and outflows: inward flows from a higher Lake Rukwa access to Lake Malawi and an exit route to the Nile have all been proposed to have existed at some point in the lake’s history.
Lake Tanganyika is an ancient lake. Its three basins which in periods with much lower water levels were separate lakes and are of different ages.
There are several islands in Lake Tanganyika. The most important of them are
Kavala Island (The Democratic Republic of the Congo)
Mamba-Kayenda Islands (The Democratic Republic of the Congo)
Milima Island (The Democratic Republic of the Congo)
Kibishie Island (The Democratic Republic of the Congo)
Mutondwe Island ( Zambia)
Kumbula Island ( Zambia)