Aconcagua, in Argentina's Mendoza Province, rises to about 6,961 metres (22,838 feet), making it the highest mountain in the Americas and the highest anywhere outside Asia. It is also the highest point in both the Southern and Western Hemispheres, and one of the Seven Summits — yet its standard route requires no technical climbing at all.
Where Aconcagua stands
Aconcagua sits in the Principal Cordillera of the Andes, in the far west of Argentina's Mendoza Province. It lies close to the border with Chile — roughly 15 kilometres from it — but the summit is entirely within Argentine territory, a point of some national pride and occasional confusion.
The mountain is protected within Aconcagua Provincial Park, established in 1983, which covers the surrounding valleys and glaciers. Access is straightforward by the standards of great mountains: the city of Mendoza lies a few hours away by road, and the paved Route 7 corridor between Mendoza and Santiago passes within sight of the peak at Puente del Inca, a natural rock bridge over thermal springs that serves as the traditional staging point. Most climbers walk in from the Horcones valley on the mountain's western side.
Its exact height has been revised repeatedly. An Argentine survey in 1989 produced a figure of 6,960.8 metres, and values between about 6,959 and 6,962 metres circulate in different sources depending on survey method and datum. The commonly cited 6,961 metres (22,838 feet) is best treated as accurate to within a couple of metres rather than as an exact number.
Not a volcano — and the reason why
Aconcagua is frequently and understandably assumed to be a volcano. It sits in the Andes, the mountain chain generated by subduction, and it is ringed by volcanic terrain. The assumption is nonetheless wrong in the present tense, and the explanation is one of the more interesting things about the mountain.
Aconcagua was an active stratovolcano, roughly 10 to 8.5 million years ago in the Miocene. That volcanic activity then ceased. What stands today is largely a great stack of older marine sedimentary rock and the remains of those volcanic sequences, thrust upward and folded by compression along the Andean front. The mountain is essentially a tectonic construction built partly out of volcanic wreckage, not an active volcanic cone.
The reason the volcanism stopped is a phenomenon called flat-slab subduction. Along most of the Andes, the Nazca Plate descends beneath the South American Plate at a steep angle, and the descending slab releases water that triggers melting in the mantle above, producing the familiar chain of volcanoes. In a segment of the central Andes spanning roughly 27° to 33° south — which includes Aconcagua — the subducting slab flattens out and travels nearly horizontally for a long distance before descending. This closes the wedge of hot mantle that would otherwise generate magma. Volcanism shut down; compression and uplift took over. The result is a segment of the Andes that is exceptionally high but conspicuously lacking in active volcanoes.
Climate and the white wind
Aconcagua's weather is the mountain's real difficulty. The peak stands in the subtropical high-pressure belt in an extremely dry setting, which produces a specific and demanding combination of conditions.
- Wind. The dominant hazard. Sustained high winds are routine on the upper mountain, and the fierce storm winds known as the viento blanco — the white wind — can pin climbers in camp for days and have been responsible for a significant share of the mountain's fatalities.
- Cold. Temperatures on the upper slopes commonly fall well below −20°C, and with wind chill the effective conditions are far more severe. Frostbite is among the most frequent serious injuries.
- Aridity. Precipitation is low and snowfall relatively modest for a mountain of this height, leaving much of the standard route as scree, rock and frozen ground rather than deep snow. Dehydration is a persistent and underestimated problem.
- Altitude. At nearly 7,000 metres, atmospheric pressure is roughly 40 per cent of that at sea level. Acute mountain sickness, high-altitude pulmonary oedema and cerebral oedema are the principal medical dangers.
The climbing season runs from roughly mid-November to March, the Southern Hemisphere summer, with the most settled conditions typically in January and February. The park is closed to climbers outside this window.
Routes and climbing history
The first recorded ascent was made on 14 January 1897 by the Swiss guide Matthias Zurbriggen, climbing alone to the summit as part of an expedition led by the British mountaineer Edward FitzGerald, who did not himself reach the top. Evidence found on the mountain suggests earlier human presence at great altitude: in 1985 the mummified remains of an Inca child were discovered at around 5,300 metres on the south-west ridge, indicating that the Inca had ascended high on the peak centuries earlier.
The Normal Route
The north-west route is the reason Aconcagua attracts thousands of climbers each season. It involves no roped climbing, no glacier travel of consequence and no technical rock or ice; it is, in essence, a very long, very high walk on scree and rock, and it is often described as the highest non-technical mountain in the world. The final section, the Canaleta, is a steep, loose, exhausting gully that most climbers remember unfondly.
That accessibility is also the mountain's danger. Because it demands no technical skill, it draws climbers with limited high-altitude experience, and altitude does not care about that. Deaths occur most years, and Aconcagua accounts for a meaningful number of fatalities among the Seven Summits, largely as a function of how many people attempt it. Summit success rates are generally reported in the range of 30 to 40 per cent, with weather and inadequate acclimatisation the usual causes of failure.
Harder ways up
- The Polish Glacier route on the north-east side, named after a 1934 Polish expedition, is a genuine mountaineering objective requiring glacier skills.
- The South Face is one of the great walls of the Andes — a sustained face of roughly 3,000 metres, first climbed in 1954 by a French team led by René Ferlet, and still regarded as a serious undertaking.
Most climbers on the Normal Route ascend without supplemental oxygen, which is standard practice at this altitude and distinguishes Aconcagua sharply from the 8,000-metre peaks.
Aconcagua compared with Denali
The most revealing comparison is not with Everest but with Denali, North America's highest peak, because the two are so often ranked by the wrong measure.
Height. Aconcagua wins outright at about 6,961 metres against Denali's roughly 6,190 metres — a difference of some 770 metres, and the reason Aconcagua rather than Denali is the Seven Summits entry for the Americas as a whole.
Cold. Denali wins this decisively, and it is not close. Denali sits at about 63° north, only a few degrees below the Arctic Circle, where the atmosphere is thinner for a given elevation and winter temperatures are brutal. Aconcagua lies at about 32° south, in the subtropics. Denali is widely considered the colder and, by that measure, the more punishing mountain despite being lower.
Relief. Denali rises more dramatically from its surroundings, with base-to-summit relief among the greatest of any mountain on land. Aconcagua stands on an already very high Andean plateau, so the visual rise is less startling.
Technical difficulty. Denali's standard West Buttress route involves glacier travel, crevasse rescue, roped movement and hauling sleds, and climbers must be self-sufficient in a genuinely remote setting. Aconcagua's Normal Route needs none of that and has mule support to base camp and a staffed park presence.
Access. Aconcagua is far easier to reach — a road approach from Mendoza against a ski-plane landing on the Kahiltan Glacier for Denali.
The upshot: Aconcagua is the higher mountain, Denali the harder one. Climbers frequently use Aconcagua as an altitude proving ground before attempting the 8,000-metre peaks, precisely because it delivers extreme elevation without technical demands. For comparison, Everest stands about 1,880 metres higher still, and Kilimanjaro, Africa's Seven Summits entry, is roughly 1,070 metres lower than Aconcagua.
Conservation, crowds and the name
Aconcagua Provincial Park manages a mountain that receives thousands of visitors each season, and the pressures are those of popularity. Waste management has been a long-running concern; permit systems, mandatory waste-carry rules and organised clean-up efforts have been introduced to address the accumulation of rubbish and human waste at the camps. Permits are required, are priced by season and route, and provide funding for rangers and for the medical staff stationed at base camp, whose altitude checks have prevented a considerable number of serious incidents.
The park's ecology is high-desert Andean: sparse vegetation, guanacos on the lower slopes, and Andean condors — among the largest flying birds in the world — riding the updraughts along the ridges. Glaciers on the mountain, including the Horcones and Polish glaciers, have been retreating, consistent with the broader pattern across the Andes, with implications for the meltwater that supplies Mendoza's vineyards and irrigation downstream.
The origin of the name is uncertain and genuinely disputed. Proposed derivations include the Quechua Ackon Cahuak, often glossed as "stone sentinel," a Mapudungun phrase meaning something like "comes from the other side," and an Aymara root. No single explanation commands consensus, and the frequently repeated "stone sentinel" translation should be treated as one plausible candidate rather than an established fact.
Key facts
- Elevation: approximately 6,961 m (22,838 ft), with surveys ranging a few metres either side
- Location: Mendoza Province, Argentina, about 15 km east of the Chilean border
- Superlatives: highest peak in the Americas, the Southern Hemisphere, the Western Hemisphere, and outside Asia
- Range: Principal Cordillera of the Andes
- Type: uplifted sedimentary and older volcanic rock — an extinct Miocene volcano, not an active one
- First recorded ascent: Matthias Zurbriggen, 14 January 1897
- Season: mid-November to March
- Standard route: the north-west Normal Route — non-technical, but at extreme altitude
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