At 3,650 metres above sea level, on the high plateau of south-west Bolivia, Uyuni is a dusty, windblown frontier town that exists for one reason. Just beyond it lies the Salar de Uyuni, the largest salt flat in the world, a blinding white plain of more than ten thousand square kilometres, which formed when ancient lakes dried out. In the rainy season, from roughly January to March, a thin film of water turns the salt into a mirror that doubles the sky, and in the dry season the surface cracks into hexagonal plates that stretch to the horizon.
Uyuni itself is rough and ready. The railway reached it early in the twentieth century, and the cemetery of old steam locomotives on the edge of town, rusted and sprayed with graffiti, is a sad and photogenic reminder of the mining trade that once passed through. The streets are wide, the wind is cold even at midday, and nights can fall well below freezing. The altitude is a real factor, so take it slowly, drink water and avoid heavy meals if your head aches. Many travellers use the town to sort out supplies before heading into the high desert.
The ride towards Laguna Colorada, about two hundred kilometres to the south, is a different order of adventure. The tracks cross the salt flat, then climb across lava fields, past volcanoes, rocky valleys and lagoons that range from turquoise to green. The surface is gravel, sand and corrugations for most of the route, and wind, cold and altitude add to the challenge. Heights of four thousand five hundred metres or more are reached, and the red-hued Laguna Colorada, at about four thousand three hundred metres, is coloured by algae and minerals and ringed by flamingos feeding in the shallows. Because tracks branch and navigation is difficult, most people go with a guide, and the salt itself, particularly when wet, corrodes metal, so the bike needs a good wash afterwards.
Fuel is the thing that matters. Uyuni has petrol stations, though supplies sometimes run low, and prices for foreigners may differ from local rates, so ask. Beyond the town, there is almost none, so carry spare fuel, water, warm clothing, and food. Bring cash in bolivianos, since cards are rarely accepted. The sunrise over the salt, with a pale pink light creeping across the white and the cold biting at your fingers, is a memory that stays.