One of five west coast, low-latitude deserts of the world, the Namib extends along the entire Namibian coastline in an 80-120 km wide belt. Its extreme aridity is the result of the cold, upwelling Benguela Current, which flows up the west coast of Africa as far as Angola, and because of its low temperatures induces very little evaporation and rainfall (<50 mm per year). It does, however, create an up to 50 km wide coastal fog belt providing sufficient moisture for the development of a specialist flora and fauna, many of which are endemic to the Namib. In addition, the lagoons at Walvis Bay and Sandwich Harbour are designated wetlands of international importance, because of their unique setting and rich birdlife, including flamingo, white pelican and Damara tern. Larger mammals like the famed desert elephant, black rhino, lion, cheetah and giraffe can be found along the northern rivers traversing the Skeleton Coast National Park. Geomorphologically, the Namib includes a variety of landscapes, including classic sand dunes, extensive gravel plains, locally with gypcrete and calcrete duricrusts, elongated salt pans, ephemeral watercourses forming linear oases,
inselbergs and low mountain ranges. Along the coast, wind-swept sandy beaches alternate with rocky stretches, in places carved into striking rock formations (e.g. Bogenfels Arch). Designated a UNESCO World Heritage Site in 2013, the "Namib Sand Sea" between Lüderitz and the Kuiseb River encompasses such well-known landmarks as Sossusvlei and Sandwich Harbour, while the fabled Skeleton Coast north of the Ugab River is notorious for its numerous ship wrecks.