Lake Victoria is the third-largest in the world (and largest in Africa), with 68,870km2 of surface water. In terms of depth, Lake Tanganyika is second in the world, at 1,470 metres. It is also the longest freshwater lake in the world (spanning Burundi, Tanzania, Zambia and DR Congo) at 676km, behind only the Caspian Sea, which is often discounted due to it containing an oceanic basin (and therefore not a true freshwater lake). In terms of rivers, the Nile (6,853km) is only just second to the Amazon River (6,9992km) in the world. The Congo river takes the 6th spot at 4,700km, whilst the Niger River comes in at 10th in the world at 4,180km in length. Altogether, Africa has the highest volume of wetlands, large lakes, reservoirs and river systems in the world, with 31,776km3.