Pissis

A 6,795-metre extinct volcano on the border between Argentina and Chile, in the Andes of the Atacama region. Pissis is the second-highest volcano in the world and the third-highest peak in the Western Hemisphere — after Aconcagua and Ojos del Salado, all three of which sit within 200 kilometres of each other in the high Andean spine. The mountain was named for the French geologist Pedro José Amadeo Pissis, who served as Chile's official cartographer in the 19th century.

The first ascent came in 1937 by a Polish expedition — the same expedition that had summited Ojos del Salado earlier in the same season. The Polish team of the late 1930s was responsible for first ascents on most of the major peaks of the Atacama Andes. Ascending in the years immediately before the war, with limited resources and minimal infrastructure, they established route knowledge that subsequent expeditions have largely followed.

The standard route from the Argentine side is technically straightforward — a long high-altitude trek with no significant technical climbing. The challenges are altitude, weather, and the extreme aridity of the approach. The Atacama is the driest non-polar place on Earth, and the high desert at 5,000 metres produces conditions that can dehydrate climbers faster than they can replenish. The mountain receives almost no snow, and the upper slopes are often loose volcanic rubble rather than firm snow or ice. The fatality rate is low. Most accidents have involved high-altitude pulmonary edema in climbers who underestimated the acclimatization required.

Pissis is climbed by perhaps a few dozen teams per year — significantly fewer than Aconcagua or Ojos del Salado. The remoteness of the approach, the multi-day drive across the Atacama to reach base camp, and the lack of commercial infrastructure have kept the mountain quieter than its neighbours. For climbers who have summited Aconcagua and want a different Andean experience, Pissis offers what its neighbours cannot — a 6700-metre peak that few people have stood on top of.