Lanín, Stratovolcano on the Argentina–Chile border, Andes

Lanín is a mountain in the Andes range on the border between Argentina and Chile. Its snow-covered slopes rise above forests of southern beech trees and form a slender cone visible from far away.

Basilio Villarino sighted the volcano in 1782 and recorded that locals called it Yajaunaujén. Radiocarbon dating places possible activity around 540 AD, and the last eruption is estimated at about 1,600 years ago. A 1906 newspaper report of an eruption was disputed by Karl Sapper in 1917; seismic movements were detected inside the volcano from 15 February 2017.

The Mapuche name Lanín may derive from Lanlil, "we sink", or mean "dead rock"; some Mapuche say it means "died of a binge". In their legend, the god Pillán lived on the summit and demanded the sacrifice of Huilefún, after which the volcano fell silent. Mapuche communities regard the mountain as sacred and do not climb it.

Hikers need permits from park authorities on the Argentine or Chilean side depending on the route. Early morning starts help with cooler temperatures and firmer snow underfoot.

The snow line shifts through the seasons so the ice cap shrinks smaller in summer months. The summit crater has no open vent but shows only gentle depressions in the snow.