Tupungato, one of the highest mountains in South America, is a massive stratovolcano dating to Pleistocene times. It lies on the border between the Chilean Metropolitan Region and the province of Mendoza, Argentina, near a major international highway about 80 km (50 mi) east of Santiago. It is located about 100 km (62 mi) south of Aconcagua, the highest peak of both the Southern and Western Hemispheres. Immediately to its southwest lies the active Tupungatito volcano, which last erupted in 1987.