San Alfonso is a village in the Cajón del Maipo, the deep valley that the Maipo River has cut into the Andes south-east of Santiago, and it sits at eleven hundred metres, where the air has already thinned and cooled compared with the city below. It belongs to the commune of San José de Maipo, and it is the kind of place where Santiagueños come on weekends to get away from the heat, with rafting, horse riding, mountain biking and long Sunday lunches built around a wood-fired grill. Nearby are the Cascada de las Ánimas, a waterfall and nature reserve, and several small hotels and campsites along the river.
The valley is the water supply of the Chilean capital, and it is a dramatic one. The river runs cloudy grey-brown with glacial silt, and the walls rise on both sides into bare, folded rock, with the snow-capped cone of the Volcán San José, at about fifty-eight hundred metres, anchoring the head of the valley. The light here is strong, the air is dry, and in the afternoon a wind blows up the valley from the plain. The vegetation is dry scrub, cacti and hardy trees, and the colours are warm browns and ochres, with green in the narrow strips beside the water.
The road, the G-25, climbs steadily from the outskirts of Puente Alto, and it is a good motorcycle road with a surface that is generally smooth and bends that tighten as the valley narrows. It is, however, the only road, so on summer weekends it is slow with Santiago traffic, and on any day you will share it with trucks serving the mines and the hydroelectric stations. Rockfalls and landslides can close sections after heavy rain or in the spring melt, so check conditions. The best times are on weekday mornings, from spring through autumn.
Fuel is the thing to settle before you leave the city. San José de Maipo, the main village of the valley, has services and is the last reasonable place to fill up, and Puente Alto, nearly thirty kilometres away, is the large town where you will find everything. San Alfonso has places to eat, from simple grills to more ambitious cooking, and the evenings are cool enough that a fire is welcome.