Mauritania, officially the Islamic Republic of Mauritania, is a country in Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to the north and northwest, Algeria to the northeast, Mali to the east and southeast, and Senegal to the southwest. By land area Mauritania is the 11th-largest country in Africa and the 28th-largest in the world; 90% of its territory is in the Sahara desert. Most of its population of some 4.3 million live in the temperate south of the country; roughly a third of the population is concentrated in the capital and largest city, Nouakchott, on the Atlantic coast.