The Namib is a broad expanse of hyper-arid gravel plains and dunes that stretches along Namibia's entire coastline. It varies between 100 km (60 miles) and many hundreds in width. Areas within the Namib include the Skeleton Coast and the Kaokoveld in the north and the extensive Namib Sand Sea along the central coast.[19] The Great Escarpment swiftly rises to over 2,000 metres (7,000 ft). Average temperatures and temperature ranges increase 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 significantly more productive than the Namib Desert. As summer winds are forced over the Escarpment, moisture is extracted as precipitation.[60] The Bushveld is found in north-eastern Namibia along the Angolan border and in the Caprivi Strip. The area receives a significantly greater amount of precipitation than the rest of the country, averaging around 400 mm (16 in) per year. The area is generally flat and the soils sandy, limiting their ability to retain water and support agriculture.[61] The Kalahari Desert, an arid region that extends into South Africa and Botswana, is one of Namibia's well-known geographical features. The Kalahari, while popularly known as a desert, has a variety of localised environments, including some verdant and technically non-desert areas. The Succulent Karoo is home to over 5,000 species of plants, nearly half of them endemic; approximately 10 percent of the world's succulents are found in the Karoo.[62] The reason behind this high productivity and endemism may be the relatively stable nature of precipitation.[63]