At 825,418 km2 (318,696 sq mi), Namibia is the world's thirty-fourth largest country (after Venezuela). After Mongolia, Namibia is the least densely populated country in the world (2.5 inhabitants per square kilometre (6.5 /sq mi)).
The Namibian landscape consists generally of five geographical areas, each with characteristic abiotic conditions and vegetation with some variation within and overlap between them: the Central Plateau, the Namib Desert, the Great Escarpment, the Bushveld, and the Kalahari Desert. Although the climate is generally extremely dry, there are a few exceptions. The cold, north-flowing Benguela current of the Atlantic Ocean accounts for some of the low precipitation.
The Namib Desert is a broad expanse of hyper-arid gravel plains and dunes that stretches along the entire coastline, which varies in width between 100 to many hundreds of kilometres. Areas within the Namib include the Skeleton Coast and the Kaokoveld in the north and the extensive Namib Sand Sea along the central coast. The sands that make up the sand sea are a consequence of erosional processes that take place within the Orange River valley and areas further to the south. As sand-laden waters drop their suspended loads into the Atlantic, onshore currents deposit them along the shore. The prevailing south west winds then pick up and redeposit the sand in the form of massive dunes in the widespread sand sea, the largest sand dunes in the world. In areas where the supply of sand is reduced because of the inability of the sand to cross riverbeds, the winds also scour the land to form large gravel plains. In many areas within the Namib Desert, there is little vegetation with the exception of lichens found in the gravel plains, and in dry river beds where plants can access subterranean water.
 Great Escarpment
The Great Escarpment swiftly rises to over 2,000 meters (6,562 ft). Average temperatures and temperature ranges increase as you move further inland from the cold Atlantic waters, while the lingering coastal fogs slowly diminish. Although the area is rocky with poorly developed soils, it is nonetheless significantly more productive than the Namib Desert. As summer winds are forced over the Escarpment, moisture is extracted as precipitation. The water, along with rapidly changing topography, is responsible for the creation of microhabitats which offer a wide range of organisms, many of them endemic. Vegetation along the escarpment varies in both form and density, with community structure ranging from dense woodlands to more shrubby areas with scattered trees. A number of Acacia species are found here, as well as grasses and other shrubby vegetation.
The Bushveld is found in north eastern Namibia along the Angolan border and in the Caprivi Strip which is the vestige of a narrow corridor demarcated for the German Empire to access the Zambezi River. The area receives a significantly greater amount of precipitation than the rest of the country, averaging around 400 mm (15.7 in) per year. Temperatures are also cooler and more moderate, with approximate seasonal variations of between 10 °C (50 °F) and 30 °C (86 °F). The area is generally flat and the soils sandy, limiting their ability to retain water. Located adjacent to the Bushveld in north-central Namibia is one of nature’s most spectacular features: the Etosha Pan. For most of the year it is a dry, saline wasteland, but during the wet season, it forms a shallow lake covering more than 6000 square kilometres. The area is ecologically important and vital to the huge numbers of birds and animals from the surrounding savannah that gather in the region as summer drought forces them to the scattered waterholes that ring the pan. The Bushveld area has been demarcated by the World Wildlife Fund as part of the Angolan Mopane woodlands ecoregion, which extends north across the Cunene River into neighbouring Angola.
 Kalahari Desert
The Kalahari Desert is perhaps Namibia’s best known geographical feature. Shared with South Africa and Botswana, it has a variety of localized environments ranging from hyper-arid sandy desert, to areas that seem to defy the common definition of desert. One of these areas, known as the Succulent Karoo, is home to over 5,000 species of plants, nearly half of them endemic; fully one third of the world’s succulents are found in the Karoo.
The reason behind this high productivity and endemism may be the relatively stable nature of precipitation. The Karoo apparently does not experience drought on a regular basis, so even though the area is technically desert, regular winter rains provide enough moisture to support the region’s interesting plant community. Another feature of the Kalahari, indeed many parts of Namibia, are inselbergs, isolated mountains that create microclimates and habitat for organisms not adapted to life in the surrounding desert matrix.
For more info, maps, images and reference please visit: , http://en.wikipedia.org/wiki/Namibia.