Chad, Lake, a large, shallow freshwater lake in north-central Africa, bordered by Chad, Cameroon, Nigeria, and Niger. Its area varies from 4,000 to 10,000 square miles (10,000–26,000 km2), depending on the season. Maximum depth is about 20 feet (6 m). Lake Chad is fed by several rivers and has no outward drainage.
Sahara, the vast desert of northern Africa, and the world's largest arid region. It occupies much of the broad northern half of Africa and covers some 3,500,000 square miles (9,000,000 km2), an area only slightly less than that of the United States.