Lake Tanganyika is the second-deepest and, by volume, the second-largest lake in the world (after Siberia's Lake Baikal in both respects). It lies in four countries' territories: a little in each of Burundi and Zambia, and more than 40 percent in each of Democratic Republic of Congo and Tanzania.
The main settlement on the lakeshore is the town of Kigoma, which is also the usual entry point to the region.Two awesome nature reserves border Lake Tanganyika: the incredibly beautiful Mahale Mountains National Park and the chimpanzee-famous Gombe Stream National Park.
Lake Tanganyika's crystal-clear water is contained within the hills of the Great Rift Valley. It is 675km long, an average of 50km wide, and 1 470m deep at its deepest point, holding about 18 900km3 of alkaline fresh water that is claimed to be the cleanest in the world. The water on the surface averages 25°C, the temperature of a warm day in Cape Town.
Lake Tanganyika is about three million years old and fed by at least 50 inlets and streams. Its only outflow, however, is the Lukuga River, which it feeds only during years of extremely high rainfall. As a body of water, it is very isolated: no similar habitats exist in the surrounding areas.
This fact, coupled with Lake Tanganyika's age, have made it one of the most biologically rich and scientifically valuable habitats in the world. More than 500 fish species live in Lake Tanganyika. However, its great depth and lack of water turnover make its depths into 'fossil water', which lacks oxygen. Almost all of Lake Tanganyika's fish therefore live above a depth of 600 feet.
This, at least, makes them easier for the locals to catch and eat. The tiny local plankton-eating dagaa is Lake Tanganyika's most economically important fish, caught in the millions and laid out on the lakeshore in the sun to dry. About a million people depend on the lake's fish output for survival, and at night you can see the tiny lights of hundreds of small fishing vessels bobbing on the lake's waters.