Incahuasi, Dormant stratovolcano in the Andes, Catamarca Province, Argentina and Atacama Region, Chile

Incahuasi is a stratovolcano on the Argentina–Chile border, 6,621 m high, formed by two coalesced cones inside a caldera 3.5 km wide. A lava dome 6 by 4 km lies on the eastern flank, and the summit crater, 750 by 900 m, sits within a 2 km-wide summit plateau. The upper slopes are pale reddish brown with snow patches; below spread tan, rounded foothills.

The mountain formed through volcanic activity spanning roughly one and a half million years. Smaller cones on the northeastern side produced lava flows that shaped the surrounding terrain.

The summit holds the "Asiento del Inca", a stone seat whose backrest is a slab set into a wall and whose armrests are stacked slabs; it is said to have served the Inca or his son. The Incas built settlements here to anchor their military and administrative control during expansion.

This region is dry with limited rainfall, mostly falling as snow during winter months. Visitors should prepare for extreme altitude conditions and harsh weather.

The summit crater, 750 by 900 metres wide, sits inside a summit plateau about 2 kilometres across, and the highest point lies on its northeastern rim. The eastern slope holds a separate arcuate crater with a lava dome.