Quimal stands alone on the western rim of the Salar de Atacama, in the Cordillera Domeyko — the old, low, dark range on the other side of the basin from the volcanoes. At 4,278 metres it is modest by local standards, but because nothing else nearby comes close to it, the summit gives you the whole picture at once: the salt flat below, the entire volcanic arc from Putana to Láscar drawn across the eastern horizon, and the Pacific haze to the west.
The ascent is a long walk rather than a climb, four to five hours up a rough track and scree from a high trailhead, and it is a genuinely quiet mountain — you will almost certainly have it to yourself. Access is by 4x4 across the salar road; there is no public transport and no water.
This one is for people who have already done the standard circuit and want a day away from minibuses. Go with a guide who knows the approach, and treat the altitude with the same respect you would on the volcanoes.