Lake Victoria or Victoria Nyanza, also known as Ukerewe and Nalubaale, is one of the Great Lakes of Africa. Lake Victoria is 68,800 square kilometers in size, making it the continent's largest lake, the largest tropical lake in the world, and the second largest fresh water lake in the world in terms of surface area. Being relatively shallow for its size, with a maximum depth of 84 m and a mean depth of 40 m, Lake Victoria ranks as the seventh largest freshwater lake by volume, containing 2,750 cubic kilometers of water. It is the source of the longest branch of the Nile River, the White Nile, and has a catchment area of 184,000 square kilometers . The lake lies within an elevated plateau in the western part of Africa's Great Rift Valley and is subject to territorial administration by Tanzania, Uganda and Kenya. The lake has a shoreline of 3,440 km, and has more than 3,000 islands, many of which are inhabited. These include the Ssese Islands in Uganda, a large group of islands in the northwest of the Lake that are becoming a popular destination for tourists.