Aconcagua is a mountain in Argentina, its northern peak is 6,959 m, the highest in South America.

The mountain is in the province of Mendoza, covering 59-68 W and 32-39 S its boundaries are marked by the Valle de las Vacas to the north and east and the Valle de los Horcones Inferior to the west and south. The mountain and its surrounds are part of the Aconcagua Provincial Park. The mountain has a number of glaciers. The most sustantial are the north-eastern or Polish Glacier and the eastern or English Glacier.

The mountain was created by the subduction of the Nazca plate beneath the South American plate during the geologically recent Andean orogeny. The origin of the name is contested, it is either from the Arauca Aconca-Hue or the Quecha Ackon Cahuak.

In moutaineering Aconcagua is technically an easy mountain if approached from the north, the 'Normal route', on this approach no actual climbing is needed although the effects of altitude are severe (atmospheric pressure is 40% of sea-level at the summit). The record for the Normal route is 5 hours and 45 minutes, set in 1991. The routes to the peak from the southern and southwest ridges are more demanding and the southern face climb is considered very tough.

The first recorded ascent was in 1897 by an expedition led by the Briton Edward Fitzgerald. The summit was reached by the Swiss Mathias Zurbriggen on January 14 and by two other expedition members a few days later.

Aconcagua' is also called a the river that cross central Chile and ends in the Pacific ocean. The valley near the river received the name of Aconcagua valley.