The Namib is a coastal desert in southern Africa. The name Namib is of Nama origin and means "vast place". According to the broadest definition, the Namib stretches for more than 2,000 kilometres (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. The Namib's northernmost portion, which extends 450 kilometres (280 mi) from the Angola-Namibia border, is known as Moçâmedes Desert, while its southern portion approaches the neighboring Kalahari Desert. From the Atlantic coast eastward, the Namib gradually ascends in elevation, reaching up to 200 kilometres (120 mi) inland to the foot of the Great Escarpment. Annual precipitation ranges from 2 millimetres (0.079 in) in the most arid regions to 200 millimetres (7.9 in) at the escarpment, making the Namib the only true desert in southern Africa. Having endured arid or semi-arid conditions for roughly 55-80 million years, the Namib is also the oldest desert in the world.
The desert geology consists of sand seas near the coast, while gravel plains and scattered mountain outcrops occur further inland. The sand dunes, some of which are 300 metres (980 ft) high and span 32 kilometres (20 mi) long, are the second largest in the world after the Badain Jaran Desert dunes in China. Temperatures along the coast are stable and generally range between 9–20 °C (48–68 °F) annually, while temperatures further inland are variable—summer daytime temperatures can exceed 45 °C(113 °F) while nights can be freezing. Fogs that originate offshore from the collision of the cold Benguela Current and warm air from the Hadley Cell create a fog belt that frequently envelopes parts of the desert. Coastal regions can experience more than 180 days of thick fog a year. While this has proved a major hazard to ships—more than a thousand wrecks litter the Skeleton Coast—it is a vital source of moisture for desert life.
The name "Sossusvlei" is of mixed origin, and roughly means "dead end marsh". Vlei is the afrikaans word for "marsh", while "sossus" is nama for "no return" or "dead end". Sossusvlei owes this name to the fact that it is an endorheicdrainage basin (i.e., a drainage basin without outflows) for the ephemeral Tsauchab River.