Africa is the world's second-largest and second most-populous continent. At about 30.2 million km² (11.7 million sq mi) including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area.Sayre, April Pulley. (1999) Africa, Twenty-First Century Books. ISBN 0-7613-1367-2. United Nations (Department of Economic and Social Affairs, population division) in 61 territories, it accounts for about 14.2% of the world's human population. The continent is surrounded by the Mediterranean Sea to the north, the Suez Canal and the Red Sea to the northeast, the Indian Ocean to the southeast, and the Atlantic Ocean to the west. There are 53 countries, including Madagascar and all the island groups.