Cerro Ojos del Salado

Nevado Ojos del Salado is a dormant complex volcano in the Andes on the Argentina–Chile border. It is the highest volcano on Earth and the highest peak in Chile. The upper reaches of Ojos del Salado consist of several overlapping lava domes, lava flows and volcanic craters, with sparse ice cover. The complex extends over an area of 70–160 square kilometres (27–62 sq mi) and its highest summit reaches an altitude of 6,893 metres (22,615 ft) above sea level. Numerous other volcanoes rise around Ojos del Salado.

Being close to the Arid Diagonal of South America, the mountain has extremely dry conditions, which prevent the formation of substantial glaciers and a permanent snow cover. Despite the arid climate, there is a permanent crater lake about 100 m (330 ft) in diameter at an elevation of 6,480 metres (21,260 ft)-6,500 metres (21,300 ft) within the summit crater and east of the main summit. This is the highest lake of any kind in the world. Owing to its altitude and the desiccated climate, the mountain lacks vegetation.

Ojos del Salado was volcanically active during the Pleistocene and Holocene, during which it mainly produced lava flows. Activity was in two phases and a depression or caldera formed in the course of its growth. The volcano was also impacted by eruptions of its neighbour to the west, Nevado Tres Cruces. The last eruption occurred around 750 CE; steam emissions observed in November 1993 may have constituted another eruptive event.

An international highway between Argentina and Chile crosses north of the mountain. Ojos del Salado can be ascended from both countries; the first ascent was made in 1937 by Jan Alfred Szczepański and Justyn Wojsznis, members of a Polish expedition in the Andes. During the middle of the 20th century there was a debate on whether Ojos del Salado or Aconcagua was the highest mountain in South America which was eventually resolved in favour of Aconcagua.