Sand-rivers

A shipwrecked sailor's only hope on this coast would have been to find one of the desert's linear oases – sand-rivers that wind through the desert to reach the coast. The Omaruru, the Ugab, the Huab, the Koichab, the Uniab and the Hoanib are the main ones. They are few and far between. Each starts in the highlands, far inland, and, although normally dry, they flood briefly in years of good rains. For most of the time their waters filter westwards to the sea through their sandy beds. Shrubs and trees thrive, supporting whole ecosystems: green ribbons which snake across seemingly lifeless plains.

Even in the driest times, if an impervious layer of rock forces the water to surface, then the river will flow overland for a few hundred metres, only to vanish into the sand again as swiftly as it appeared. Such watering places are rare, but of vital importance to the inhabitants of the area. They have allowed isolated groups of Himba people to stay in these parts, whilst also sustaining the famous desert populations of elephant and black rhino.

In many of these river valleys there are thriving populations of gemsbok, kudu, springbok, steenbok, jackals, genets and small wild cats. The shy and secretive brown hyena is common, though seldom seen. Giraffe and zebra are scarce residents, and even lion or cheetah will sometimes appear, using the sand-rivers as alleys for hunting forays. Lion used to penetrate the desert right to the coast to prey on seals. Although it is many years since the last such coastal lion was seen, rising game populations in the interior are encouraging a greater population of lion in the region, so perhaps we'll see individuals on the beaches again before too long.

Beside the sea

Outside the river valleys, the scenery changes dramatically, with an outstanding variety of colours and forms. The gravel plains – in all hues of brown and red – are bases for occasional coloured mountains, and belts of shifting barchan sand-dunes.

Yet despite their barren appearance, even the flattest of the gravel plains here are full of life. Immediately next to the sea, high levels of humidity sustain highly specialised vegetation, succulents like lithops, and the famous lichens – which are, in fact, not plants at all but a symbiotic partnership of algae and fungi, the fungi providing the physical structure, while the algae photosynthesise to produce the food. They use the moisture in humid air, without needing either rain or even fog. That said, frequent coastal fogs and relatively undisturbed plains account for their conspicuous success here.

In some places lichens carpet the gravel desert. Take a close look at one of these gardens of lichen, and you'll find many different species, varying in colour from bright reds and oranges, through vivid greens to darker browns, greys and black. Most cling to the rocks or the crust of the gypsum soil, but a few species stand up like the skeletons of small leafless bushes, and one species, Xanthomaculina convolute, is even windblown, a minute version of the tumbleweed famous in old Western films.

All come alive, looking their best, early on damp, foggy mornings. Sections appear like green fields of wispy vegetation. But if you pass on a hot, dry afternoon, they will seem less interesting. Then stop and leave your car. Walk to the edge of a field with a bottle of water, pour a little on to a small patch of lichens, and stay to watch. Within just a few minutes you'll see them brighten and unfurl.

Less obvious is their age: lichens grow exceedingly slowly. Once disturbed, they take decades and even centuries to regenerate. On some lichen fields you will see vehicle tracks. These are sometimes 40 or 50 years old – and still the lichens briefly crushed by one set of wheels have not re-grown. This is one of the main reasons why you should never drive off the roads on the Skeleton Coast.

Further inland

East of the coastal strip, between about 30 and 60km inland, the nights are very cold, and many mornings are cool and foggy. However, after about midday the temperatures rocket and the humidity disappears. This is the harshest of the Namib's climatic zones, but even here an ecosystem has evolved, relying on occasional early-morning fogs for moisture.

This is home to various scorpions, lizards, and tenebrionid beetles, living from wind-blown detritus and vegetation including dune-creating dollar bushes, Zygophyllum stapffii, and perhaps the Namib's most fascinating plant, the remarkable Welwitschia mirabilis.