Africa, the second largest continent, has 54 countries - the most on any continent, and a surface area of 30,244,050 sq km (11,677,293 sq mi). Its highest point is Tanzania's Mt. Kilimanjaro, the world's highest free-standing mountain, which rises to 5,895 m (19,340 feet) above sea level. Africa's lowest point is Djibouti's Lake Assal, whose surface is 157 m (515 feet) below sea level. Africa has extensive mineral resources, including gold, diamonds and copper. Its longest river, the Nile, is also the World's longest, and runs 6,650 km (4,132 miles) from Burundi to Egypt. Its largest lake is the 69,485 sq km (26,828 square mile) Lake Victoria, which is surrounded by Uganda, Tanzania, and Kenya. Africa is bounded by the Mediterranean Sea to the north, by the Atlantic Ocean to the west, by the Red Sea to the northeast, and by the Indian Ocean to the southeast.