Cerro Purico Ascent [5,703 m]: Ignimbrite Country at Chajnantor

The Cerro Purico ascent (5,703 m.a.s.l., with IGM and SRTM map elevations ranging from 5,690 m to 5,703 m) is one of the most solitary and inhospitable high-mountain expeditions on the altiplano around San Pedro de Atacama. About 50 km east of the village, this massif gives its name to the Purico Volcanic Complex, an impressive pyroclastic shield that dominates the eastern edge of the Atacama Puna. Unlike well-defined stratovolcano cones such as Licancabur Volcano (5,916 m) or Láscar Volcano (5,592 m), Purico is a cluster of dacitic and andesitic extrusive domes sitting on the Chajnantor plateau. On our expeditions we have found that getting up its lapilli scree and loose blocks takes solid physical endurance and flawless prior acclimatization, and it rewards the climber with a 360° panorama over the Salar de Atacama and the astronomy plateau.

Geographically, the main summit crowns the heart of the ignimbrite plateau created by Pleistocene pyroclastic eruptions, sharing the horizon with neighboring mountains such as Cerro Chajnantor (5,640 m) and Cerro Toco (5,604 m).

Cerro Purico Fact Sheet

Guide's note from the field: "Cerro Purico is deceptive from a distance because its slopes rarely exceed 30° to 35°, but starting to walk at 4,900 meters is unforgiving. On the banks of lapilli and loose ash, the trick is to zigzag looking for outcrops of solid lava and fixed blocks instead of the soft sand that wears out your calves. Check the exact physiological impact at this altitude with our altitude to oxygen calculator."

Geological Setting and Unique Astronomical Character

Unlike the isolated stratovolcanoes of the Andean divide, Cerro Purico has singular geological and astronomical features:

1. The Purico Ignimbrite and the Plateau of Fire: The mountain gave rise to the geological term Purico Ignimbrite, the product of colossal pyroclastic flows deposited during the Pleistocene. The summit is a cluster of dacite and andesite extrusive domes that emerged at the center of this vast volcanic plateau.
2. Close to the Astronomy Infrastructure: It lies next to the Chajnantor plateau, the 5,000 m high plain that hosts the ALMA radio observatory and cosmology experiments such as the Simons Observatory and the Atacama Cosmology Telescope (ACT) on the slopes of neighboring Cerro Toco.
3. A Sense of Isolation and Open Space: Because it does not rise from the altiplano as a sharply defined vertical cone, the relief gives an immense, open horizon, free from the tourist crowds of other commercial routes.

Acclimatization Strategy and Altitude Progression

Since the walk starts directly at 4,800 to 5,000 m.a.s.l., Cerro Purico is not a beginner summit for your first or second day in the area. It requires a well-structured acclimatization program with gradual ascents to intermediate altitudes.

Suggested Altitude Progression Itinerary

You can estimate your walking pace from the elevation gain with our Naismith calculator and assess how ready you are with the summit feasibility calculator.

Logistics, 4x4 Access and Terrain Restrictions

Access to Cerro Purico requires rigorous vehicle and logistics planning:

• Vehicle Route (4x4 Mandatory): We leave San Pedro de Atacama on International Route 27-CH (the road to Paso Jama). Around kilometer 40 to 45, we turn off onto unpaved secondary tracks of gravel, severe washboard and banks of volcanic sand heading south/southeast. A 4x4 with low range (4WD), high ground clearance and reinforced tires is essential to avoid cuts from the dacite rock.
• Base Parking: The vehicle is left between 4,800 and 5,000 m.a.s.l. at the foot of the mountain's northern or western slopes.
• Astronomy Restrictions and Concessions: Given the proximity of astronomical and scientific facilities on the Chajnantor plateau, it is vital to check beforehand that the approach line does not cross operations perimeters or restricted antenna zones where institutional accreditation or an escort is required.

Hour-by-Hour Ascent Itinerary

We leave San Pedro de Atacama before dawn to get on the mountain early and summit before midday, ahead of the strong thermal winds of the altiplano:

Required Gear

Check the recommendations in our mountain gear guide to get your clothing ready:

Three-Layer System

• Base layer: Quick-drying thermal top and tights (merino wool or high-performance synthetic).
• Mid layer: Technical fleece jacket or dense windproof softshell.
• Outer layer and insulation: Down jacket (minimum 700 fill power) and waterproof shell (Gore-Tex or equivalent).

Footwear and Accessories

• Mountain boots: Stiff or semi-stiff high-cut boots with a high-grip sole to protect your ankles on loose rock.
• Telescopic poles with baskets: Essential for traction on Andean scree and to cushion your knees on the way down.
• Eye protection: Category 4 sunglasses are mandatory because of the extreme UV radiation recorded on the Chajnantor plateau.
• Gloves and hat: Thermal gloves, heavy insulated mittens and a balaclava or hat against the icy wind.
• Communication: Satellite communication device (the area has no cell signal at all).

Safety Protocols and Services Included with Vulcano

• ✅ Certified Guides: High-mountain guides with WFR / WAFA accreditation and long experience in the Atacama Puna.
• ✅ 4x4 Mountain Transport: Off-road vehicle equipped for high-altitude tracks and rocky terrain.
• ✅ Physiological Monitoring: Preventive checks of blood oxygen saturation (oximetry) and pulse at every milestone on the route.
• ✅ Satellite and Emergency Safety: Garmin InReach satellite communicator, first-aid kit and a backup medical oxygen cylinder in the vehicle.
• ❌ Not Included: Personal mountain gear, tips, or personal medical/rescue insurance.

Frequently Asked Questions

Does Cerro Purico require technical climbing skills or crampons?
No. The normal route is a walk over sloping ground, scree and dacite blocks with no exposed climbing moves. Unless there has been recent winter snowfall or ice, it is done 100% on foot without crampons.

Why is strict acclimatization required if the walk only takes 4 to 6 hours?
Because the walk starts at close to 5,000 m.a.s.l. Starting an uphill hike directly at that altitude without prior acclimatization exposes the body to a high risk of acute mountain sickness (AMS).

Can the ascent be done without a 4x4 vehicle?
No. The access tracks cross ground with sharp dacite rocks, deep washboard and sand banks where conventional vehicles or SUVs without low range destroy their tires or get stuck.