Las Leñas opened in July 1983, rising fast in a remote Andean valley - construction had begun only that January, and by midwinter a 300-bed hotel stood ready for guests. Everything here sits high. The base lodge rests at 2,240 metres, and the lifts climb to a summit near 3,430 metres, a vertical drop of nearly 1,190 metres. Because of the altitude, the entire mountain lies above the tree line; there is not a single wooded trail. The result is a landscape of bare white slopes and rock, open to the sky in every direction, where snow conditions and wind can change the character of the whole mountain in an afternoon.

Roughly a third of the marked runs at Las Leñas are rated expert, but the marked runs are not really the point. The Marte chair - its name the Spanish word for Mars - is regarded among serious skiers as the master key to freeskiing in the Andes. From its top, the off-piste possibilities run into the hundreds: steep chutes, vast bowls, and lines like the famous Eduardo's Couloir falling away at nearly 48 degrees. The terrain is so intricate that mountaineer Thomas Perren mapped and catalogued the routes, more than 200 of them, so that visitors could find their way through the maze. It has earned Las Leñas a reputation, among those who chase such things, as some of the best advanced skiing in the world.

That same terrain demands respect. Some of the chutes that look so inviting from the lift end abruptly at cliffs, and a wrong turn can leave a skier cliffed-out with no safe way down. The resort requires helmets, and experienced visitors hire certified guides who carry local knowledge of which line goes and which one ends in air. Avalanche danger is real on these loaded, treeless faces. The freedom of Las Leñas - the empty bowls, the untouched snow - is inseparable from its seriousness. The mountain rewards skill and punishes carelessness, and the people who love it most are the ones who treat it with the most caution.

Not everyone comes to ski the abyss. Near the village, gentle slopes by the Poma lifts give beginners and families room to learn, and runs close to the lodge stay lit for night skiing until late. A ski school teaches in several languages and runs programs for children as young as infancy. When the snow melts, between November and May, the valley reopens for mountain biking, horse riding and climbing. The nearest town is Malargüe, about 80 kilometres away, where many visitors sleep for cheaper rooms and discounted passes; the closest commercial airport is at San Rafael, a couple of hours' drive down the mountain roads.