Africa is the second largest continent, with 54 countries and a surface area of 30,244,050 sq km (11,677,293 mi2). Its highest point is Tanzania's Mt. Kilimanjaro, which rises to 5,895 m (19,340 feet) above sea level. Africa's lowest point is Djibouti's Lake Assal, whose surface is 515 feet (157 m) below sea level. Africa has extensive mineral resources, including gold, diamonds, and copper. Its longest river is the Nile, which runs 6,650 km (4,132 miles) from Burundi to Egypt.