At the very northwestern border of South Africa and Namibia lies the most arid and remote mountain region in South Africa: Richtersveld. This, my friends, is true adventure territory.
Richtersveld is where you'll find the world's largest variety of water-retaining plants (think cacti), precipitous canyons, rugged peaks, and a multi-hued rock and mineral landscape. There are a few lengthy hiking routes available (we're talking at least a few days), with an opportunity to encounter a vast range of bird and animal species, as well as the transhumant (seasonally migratory) Nama people, who move their livestock from place to place in the desert so as not to overgraze.
Other areas of interest include Wondergat, a sink-hole near Cornellskop known in local mythology as the home of a large, shape-shifting snake; as well as the Orange River, which is the only source of water in the region and a great place for rafting and other water travel. Peruse the included website for more information on accommodation, guided hikes, the best times to explore the region, and more.