Outside Asia there is no higher mountain than Aconcagua. At 6,961 metres it is the highest in both Americas and in the southern hemisphere, and yet you need no rope, no crampon technique and no climbing experience for it.
That makes it treacherous. Aconcagua is one of the few near seven thousand metre peaks within reach of someone with no mountaineering background, and precisely for that reason there are people on it who are not ready for it. This article is about what the mountain does ask.
The Vacas valley: the long way
There are two ways to approach Aconcagua. The short one, through the Horcones valley, is the busy one. The long one, through the Vacas valley, takes several days more and is considerably quieter.
Those extra days are not a detour but the whole point. You walk into a broad, dry valley with mules carrying the heavy loads, along a river grey with glacial silt, between walls that grow higher every day. You ascend slowly, and that is exactly what your body needs.
Along the way you see almost no one. The Vacas valley is the side of the mountain where it still feels like an expedition rather than a queue.
The wind is the real danger
Aconcagua stands almost alone at the edge of the Andes, with the Pacific on one side and the pampa on the other. There is nothing to break the wind.
There is a local name for what happens then: the viento blanco, the white wind. A storm of driven snow in which visibility drops to a few metres and the wind chill falls far below minus thirty. At the highest camps it can last for days.
That is why a nineteen day programme is necessary. Not because the climbing takes that long, but because you have to be able to wait. Anyone with only two chances at a summit day lets the weather decide. Anyone with five decides for themselves.
Penitentes
On the higher slopes you cross fields of penitentes: tall, narrow blades of snow all leaning the same way, towards the sun. They form because at altitude, in dry air, the sun makes snow evaporate directly rather than melt.
They can grow to head height and they are not just a fine sight. Crossing a field of penitentes is slow, tiring work. It is the kind of obstacle that appears on no map.
On this mountain, waiting is the work. Days in a tent while it blows outside feels like waste, but it is exactly why we reach the top. The most dangerous person in the group is the one who wants to push then.
Koen De Leeuw, expedition leader
Altitude is the whole task
Almost seven thousand metres is a different category from the mountains most people start with. At the summit the oxygen pressure is roughly forty per cent of that at sea level.
What that does: you sleep badly at the highest camps, your appetite disappears exactly when you need the calories most, and you no longer recover between days. The expedition therefore works on the principle of climbing high and sleeping low, carrying gear up to a higher camp and descending again to sleep. It feels inefficient and it is the reason people reach the top.
The honest figure: of everyone who attempts Aconcagua, a minority reach the summit. That is rarely down to technique and almost always down to altitude or weather.
Why December and January
In the southern hemisphere that is high summer, and it is the only realistic window. Outside that season, cold and wind put the mountain out of reach.
Even within the window it remains high mountain terrain at almost seven kilometres: snowfall in January is normal, and the nights at the highest camps always freeze.
The most time and the most patience
Aconcagua is rated Challenge (4 out of 5) and lasts nineteen days. Of all the destinations we offer, this one asks the most time and the most patience.
You need no technical mountaineering experience, but you do need previous experience at altitude, strong base fitness and the ability to endure discomfort for weeks on end without losing your temper. That last point is no side issue: on a nineteen day expedition the mood of the group is a safety factor.
And you have to be able to handle the possibility of turning back a hundred metres from the summit because the weather shifts. Anyone who cannot live with that should choose a lower mountain.
Practical
The Aconcagua expedition runs from December 2027 to January 2028 and lasts nineteen days, via the Vacas valley. All the details are on the page for the Aconcagua expedition.
Want to see the destinations side by side: which expedition suits you compares them on terrain and intensity. And the packing list for an expedition goes into detail on what has to come along.