Hoggar (Ahaggar) Mountains:
The Hoggar Mountains, also known as the Ahaggar, are a highland region in central Sahara, or southern Algeria, along the Tropic of Cancer. They are located about 1,500 km (900 mi) south of the capital, Algiers and just west of Tamanghasset. The region is largely rocky desert with an average altitude of more than 900 metres (2,953 feet) above sea level. The highest peak is at 3,003 meters (Mount Tahat).
It's about 100,000 sq. miles (259,000 sq. km) in size and covers much of Botswana, the southwestern region of South Africa and all of western Namibia. The desert plateau is criss-crossed by dry rivers beds and dense scrub. A few small mountain ranges are situated here including the Karas and the Huns. Large herds of wildlife are found in the Kalahari Gemsbok National Park, located in South Africa near its border with Namibia.
The Namib is a coastal desert in southern Africa that stretches for more than 2,000 km (1,200 mi) along the Atlantic coasts of Angola, Namibia, and South Africa, extending southward from the Carunjamba River in Angola, through Namibia and to the Olifants River in Western Cape, South Africa. From the Atlantic coast eastward, the Namib gradually ascends in elevation, reaching up to 200 km (120 mi) inland to the foot of the Great Escarpment.
Annual precipitation ranges from 2 mm (0.079 in) in the most arid regions to 200 mm (7.9 in) at the escarpment, making the Namib the only true desert in southern Africa. The Namib is also the oldest desert in the world and its geology consists of sand seas near the coast, while gravel plains and scattered mountain outcrops occur further inland.
The desert's sand dunes, some of which are 300 m (980 ft) high and span 32 km (20 mi) long, are the second largest in the world after the Badain Jaran Desert dunes in China