Volcán Llullaillaco

Volcán Llullaillaco rises 6,739 metres on the Argentina–Chile frontier — often ranked the world's second-highest active volcano — and near its summit in 1999, archaeologists found the best-preserved Inca offerings known: three children of the capacocha ceremony, kept five centuries by cold, altitude and utter dryness. They rest now in Salta's MAAM museum, held as heritage under care and continuing debate; the mountain that held them remains largely unreached.

The summit sanctuary is the highest archaeological site known anywhere, protected as an Argentine national monument — closed ground in its own right, never part of any itinerary. The mountain around it is a serious high-altitude undertaking: expeditions run as guided, multi-day arrangements made through operators and the relevant authorities, with camps above five thousand metres, long acclimatisation in the puna, and rescue infrastructure effectively absent. The climbing is more altitude than technique, which makes it no less serious. The volcano last erupted back in the 1800s and still counts as active; from its upper slopes on a clear day, a dozen other volcanoes stand across the Puna de Atacama into Chile. The base approach from San Antonio de los Cobres is an expedition before the expedition.