Aconcagua
Aconcagua (), with a summit elevation of , is the highest mountain in both the Southern and Western Hemispheres. It is located in the Andes mountain range, in the Mendoza Province, Argentina, and lies northwest of its capital, the city of Mendoza, about from San Juan Province and from the international border with Chile. The mountain itself lies entirely within Argentina, immediately east of Argentina's border with Chile. Its nearest higher neighbor is Tirich Mir in the Hindu Kush, away. It is one of the Seven Summits.
Llullaillaco
Llullaillaco is located in the northwestern Argentine Andes, towards the southern end of the Puna. The border between Argentina (Salta Province) and Chile crosses the volcano. It lies in the Puna de Atacama, a region of very high volcanic peaks on a high plateau close to the Atacama Desert, one of the driest places in the world.
The volcano is an imposing mountain, rising by above the Salar de Punta Negra away. With a summit height of , or alternatively , it is the second highest active volcano in the world after Ojos del Salado (, ). The height of the mountain and the clear air in the region make Llullaillaco visible from Cerro Paranal, 189 km away as measured by Google Maps. The region is dry and located at high altitudes, making work in the area difficult.