Lake Edward is one of the great lakes of Africa lying in the western Rift Valley. Its length is about 65 km and the maximum width is 38 km. The deepest region is a trench only 5 km from the western shore from which the escarpment rises precipitously to highlands exceeding 2,500 m in altitude. The eastern side of this trench is much less steep and rises with an almost uniform gradient for more than 30 km under water to the Uganda shore.

The Main inflows to Lake Edward are the Nyamugasani River, which drains the southwestern end of the Rwenzoris, and Ishasha, Rutshuru and Rwindi Rivers from the Kigezi and Rwanda highlands and the Virunga volcanoes in the south. The annual contribution from the Kazinga Channel is probably small compared with that from the rivers. The amount of water flowing through the lake, exclusive of evaporation, can be seen at the outflow via the Semliki River at Ishango in the northwest which is 30-40 m wide. The water leaves the lake as a rapid and turbulent stream about 3 m deep over rocks and boulders. It is so clear that the hippopotamus can be observed under water and large numbers of Barbus are seen facing the current.

The eastern half of Lakes Edward and George is surrounded by the Rwenzori National Park of Uganda. The western half of Lake Edward, including the outflowing Semliki River, is encompassed by the Parc National de Zaire (Parc National des Virunga). This whole vast region of national parks from Lake Albert to Kivu - the Great Rift Valley with its lakes, game plains and precipitous escarpments, the glaciated Rwenzoris and partially extinct Virunga volcanoes, the tropical rainforests of Semliki Valley, the mountain forests above 3,000 m and the alpine highlands above 3,800 m - present some of the most dramatic and beautiful scenery in Africa and, with its great variety of organisms and of conditions of existence, is of extreme interest to land and water ecologists (Q, 1)