Fish River Canyon is the largest canyon in Africa, in the ǁKaras region of southern Namibia, 160 kilometres long, up to 27 wide and 550 metres deep, a gorge of grey and ochre rock cut by a river that flows only after the summer rains, seen from a line of lookouts along its rim and walked along its floor on one of the great multi-day hikes of the continent. The canyon began as a rift in the crust some 500 million years ago, deepened by glaciers and then by the river, which now runs in a chain of pools and dry sand through the winter, and its scale is what is seen: from the main viewpoint above Hobas the walls fall to a river winding in loops far below, and in the cool of early morning, before the sun floods the gorge, the terraces just under the rim are scanned for klipspringer and the wild horses and zebra that come to the pools. A path runs along the unfenced edge between the viewpoints, through aloes, shrubs and loose plates of rock, and every few hundred metres the angle changes and another set of bends comes into line, with the sunset colouring the far wall.
The hike is the canyon's test. From Hikers' Viewpoint the trail begins with a chain-assisted scramble down the first steep hundred metres, then some 85 kilometres of sand, boulder-hopping and river crossings over four or five days to the hot springs at ǀAi-ǀAis, whose name means burning water in Nama, carrying everything, with the river pools for water and the stars for a roof; it is open only from May to September, when the heat is bearable, and needs a medical certificate. On the rim stand the quiver trees, not trees but giant aloes, whose soft fibrous branches the San hunters hollowed out to carry their arrows, and in midwinter they push up yellow flower spikes heavy with nectar that sunbirds crowd and baboons strip. Fish River is a canyon that Africa keeps quiet, and the walk along its floor is the way to earn it.