evidence: The South African central plateau contains only two major rivers: the Limpopo (a stretch of which is shared with Zimbabwe), and the Orange (with its tributary, the Vaal) which runs with a variable flow across the central landscape from east to west, emptying into the Atlantic Ocean at the Namibian border. [...] Some of the more prominent towns in this area are Springbok, being the capital of this region, as well as Kleinzee and Koiingnaas, both private mining towns owned by De Beers Diamond Mines. This area is rich in alluvial diamonds, deposited along the coast by the Orange River. Oranjemund is another mining town along this coast, situated in Namibia, but very much on the border. As the name suggests, it is at the mouth of the Orange River which forms the border between South Africa and Namibia. The town of Alexander Bay is located on the opposite side of the river mouth (i.e. in South Africa) and is linked to Oranjemund by the Ernest Oppenheimer Bridge. Other links crossing the river further upstream are a reintroduced pontoon at Sendelingsdrift in the Richtersveld National Park, and road bridges at Vioolsdrif (the main border crossing between the two countries) and at the remote border crossing of Onseepkans. [...] - Westernmost Point: Orange River Mouth (near Alexander Bay), Northern Cape (28°37′50″S 16°27′0″E / 28.63056°S 16.45000°E)