Seismiles Route in Chile: Definitive Guide, 4x4 Logistics and Summits

The Seismiles Route in Chile follows the international highway CH-31, linking the city of Copiapó with Paso San Francisco at 4,726 m in the Atacama Region. This Andean corridor holds the highest density of volcanoes above 6,000 meters on the planet, crowned by Nevado Ojos del Salado (6,893 m). Unlike the Argentine side, the Chilean side has no intermediate towns at altitude at all, so you have to be fully self-sufficient in fuel, drinking water, thermal gear and emergency response.

At Vulcano Expediciones, with 27 years guiding expeditions in the high Puna de Atacama, we wrote this field-based technical guide to help you plan the 4x4 logistics, the acclimatization itinerary and the ascent of the most impressive volcanoes in South America.

What Is the Seismiles Route in Chile?

The Seismiles Route in Chile is a 280-kilometer mountain route that joins Copiapó (800 m) with the international border at Paso San Francisco. Along this mountain road rise more than 20 summits above 6,000 m, among them Ojos del Salado, the Tres Cruces massif and Incahuasi volcano.

The Chilean side of the Seismiles is not a conventional paved tourist circuit: it is a high-mountain expedition in remote terrain with no cell signal, no gas stations and no mechanic services beyond kilometer 40.

 Copiapó (800m)
   │
   ├─► Km 155: Salar de Maricunga & Laguna Santa Rosa (3,760m)
   │
   ├─► Km 170: Maricunga Border Complex / Carabineros (3,700m)
   │
   ├─► Km 265: Laguna Verde (4,340m) [Main Base Camp]
   │     │
   │     ├─► Valle Ancho turnoff ➔ Refugio Atacama (5,200m) ➔ Refugio Tejos (5,837m)
   │     └─► Summit access: Barrancas Blancas, Vicuñas, Tres Cruces
   │
   └─► Km 280: San Francisco International Pass (4,726m) ➔ San Francisco Volcano (6,018m)

Compared with the Seismiles Route in Argentina, which has lodging and supplies in Fiambalá, access from Copiapó means carrying all your logistics from the base level before you head into the high desert.

Key Acclimatization Points and Camps

Going straight from sea level or from Copiapó (800 m) to elevations above 4,000 meters causes severe acute mountain sickness (AMS). On our expeditions we structure the advance in gradual stages so the body can adapt to hypoxia.

1. Salar de Maricunga and Laguna Santa Rosa (3,760 m)

Located in Nevado Tres Cruces National Park, this altiplano wetland is home to flamingo and vicuña populations. Spending the night at the CONAF ranger station or in a tent next to the lagoon steadies your oxygen saturation. We recommend an acclimatization hike up Cerro Maricunga (4,885 m) before continuing by vehicle to Laguna Verde. From this area you can also connect northward with the Salar de Pedernales and Laguna Turquesa tour via Vega San Andrés.

2. Laguna Verde (4,340 m)

This is the nerve center of the Seismiles Route. Surrounded by thermal pools at 38 °C and facing the south wall of the Tres Cruces massif, this endorheic basin is the strategic base for progression ascents to 5,000 m and 6,000 m elevations. For those who won't be climbing and want to visit for the day, we run the tour to Laguna Verde and hot springs from Copiapó in a 4x4 truck with a guide and oxygen support. Night temperatures in the summer season often drop to -15 °C with sustained westerly winds above 50 km/h.

Field Experience: At Laguna Verde the thermal wind funnels in violently from 13:00 on. Pitch your tent with heavy rock anchors on the guy lines before noon, so the gusts don't snap the aluminum poles.

Iconic Summits of the Chilean Seismiles

The Copiapó mountain sector holds the largest concentration of giant volcanoes in the Western Hemisphere. Each summit demands a different level of technical preparation and logistics.

Nevado Ojos del Salado (6,893 m)

The second-highest summit in the Americas and the highest elevation in Chile. The ascent by the normal Chilean route runs from Refugio Atacama (5,200 m) to Refugio Tejos (5,837 m). Summit day means climbing 1,050 meters of elevation gain on volcanic scree, crossing the main crater and getting over the final rock wall with a 30-meter rock-climbing pitch graded II° UIAA. For an in-depth comparison with the roof of the Americas, see our analysis in Ojos del Salado vs. Aconcagua and the assessment of The Final Chimney of Ojos del Salado.

Nevado San Francisco (6,018 m)

Located next to Paso Internacional San Francisco, it is the most accessible 6,000 m peak in the area. Its vehicle approach lets you start walking at more than 4,700 m, which makes it the ideal test summit within the Acclimatization Itinerary for Ojos del Salado.

4x4 Logistics, Fuel and Range

Reaching the Puna base camps requires vehicles prepared for extreme conditions. A mechanical failure at 4,500 m with no phone signal is a real emergency. To coordinate the vehicle and hut aspects, see our guide to 4x4 Logistics, Huts and Driving Guide on the Seismiles Route. If you want to go deeper into the most remote circuits away from the main road toward Cañón del Juncalito and Sierra Nevada, check the guide to the Lagunas Bravas 4x4 Traverse.

1. 4x4 Vehicle Requirements

• Transfer case with low range (4L): Urban AWD systems without low range overheat and get stuck in the volcanic sand of the turnoff to Refugio Atacama.
• All-Terrain (A/T) or Mud-Terrain (M/T) tires: Minimum 10-ply (Load Range E). Basalt rocks cut the sidewalls of conventional tires.
• Two full-size spare tires, mounted: Both wheels must be the same size and have their pressure checked before leaving Copiapó.
• Recovery gear: High-flow 12V compressor, analog pressure gauge, traction boards (Maxtrax), 9-meter strap (8 tons), steel shackles and Hi-Lift jack.

2. Fuel Consumption and Power Loss at Altitude

The lower oxygen density at 4,500 m reduces the power of naturally aspirated engines by 35% to 45%. As a result, fuel consumption rises by up to 50% because of continuous use of low gears on gravel and sand stretches.

• Full load in Copiapó: Fill the main tank and carry 60 to 80 additional liters in approved metal Jerrycan-type cans.
• Anti-gel additive for diesel engines: Mix the additive into the tank when you refuel in Copiapó, to keep the fuel's paraffin from freezing at -20 °C.
• Check how much power your vehicle loses with the 4x4 Altitude Power Loss Calculator.

Technical Gear, Clothing and Outdoor Calculators

The climate in the Puna de Atacama combines extreme solar radiation during the day with freezing temperatures and gusts of white wind at night.

Layering System for the Puna

1. Base Layer: Merino wool long-sleeve shirts and long underwear (200-260 g/m²) for moisture transport and insulation.
2. Mid Layer: Technical fleece or synthetic-fiber jacket (PrimaLoft/Polartec).
3. Thermal Insulating Layer: High-mountain down jacket with more than 800 fill power and baffle box construction.
4. Outer Layer: Waterproof/windproof membrane jacket and pants (3-layer Gore-Tex Pro or equivalent).
5. Footwear: High-mountain double boots with removable inner boot and a rigid sole compatible with automatic crampons.

See the detailed clothing and gear requirements in the Gear and Clothing List for Ojos del Salado.

Outdoor Tools and Calculators

To get the most out of planning your expedition, you can use our interactive tools: explore the mapping and huts on the Interactive Map of the Seismiles Route, calculate the impact of wind speed with the Summit Window and Wind Chill Calculator, estimate the fuel you will burn to get drinking water with the Snow Melting, Water and Fuel Calculator and check the limits of your gear with the Sleeping Bag and R-Value Calculator.

When to Go? Weather, Windows and Seasonality

The date you choose for the expedition determines road access and your chances of reaching the summit. See the full weather report in Best Time to Climb Ojos del Salado: Weather and Wind.

• November to December (Main Window): Optimal period. Moderate winds, less snow buildup on the 4x4 tracks and atmospheric stability.
• January to March (Altiplano Winter): Convective storms linked to Amazonian moisture form in the afternoons. Heavy snowfall, thunderstorms and frozen gullies can occur in the Maricunga area.
• April to October (Austral Winter): Extremely hostile conditions. Temperatures below -25 °C and hurricane-force winds above 100 km/h often force closures of Route CH-31 because of snow accumulation.

Mandatory Permits and Legal Procedures

To climb volcanoes located on the border between Chile and Argentina, you must comply with current legal regulations:

1. DIFROL Permit (Chile's Directorate of Borders and Boundaries): Mandatory for all foreign climbers. It must be processed online weeks in advance. See the detailed guide to DIFROL and CONAF Permits for Ojos del Salado.
2. Safe-Conduct and Registration with Carabineros: Mandatory in-person notification at the Maricunga Border Complex (km 170), stating names, itinerary, vehicle license plates and return date.
3. Satellite SOS Communication: Mandatory device (Garmin InReach, ZOLEO or Spot) set up to send real-time position and receive weather alerts.

To estimate the costs of permits, vehicles and professional guides, see our breakdown in How Much Does It Cost to Climb Ojos del Salado? Real Cost Breakdown and look at the organizational differences in Ojos del Salado Without a Guide vs. Guided Expedition.

Frequently Asked Questions (FAQ)

Can you do the Seismiles Route in a 4x2 or a sedan?

No. You can only drive the paved CH-31 to Paso San Francisco. To reach Laguna Santa Rosa, enter Laguna Verde or approach Refugio Atacama, a 4x4 vehicle with low range (4L) and adequate ground clearance is strictly mandatory.

Is there drinking water at the camps along the route?

There is no drinking water on the Seismiles Route. The water at Laguna Santa Rosa and Laguna Verde is brackish and high in minerals. At Refugio Atacama and Tejos you get water by diverting penitentes snow. You must carry all your water (4 to 5 liters per person per day) from Copiapó.

Do you need prior technical experience to climb the volcanoes on the route?

For introductory summits such as Nevado San Francisco or Cerro Barrancas Blancas you need excellent fitness and good acclimatization. For Nevado Ojos del Salado and Tres Cruces Sur you must know how to use crampons and an ice axe, walk on steep scree and have a notion of easy rock climbing above 6,800 m.

Related Guides and Articles

• 📌 Interactive Map of the Seismiles Route: Explore 6,000 m volcanoes, 4x4 huts, lagoons and routes between Chile and Argentina.
• 📌 Guide to Volcanoes: What They Are, Types and Eruptions: Find more technical tips and information on this topic in our specialized guide.
• 📌 The 10 Most Incredible 6,000 m Peaks in the World: Discover the most spectacular peaks above 6,000 meters on the planet.
• 📌 Seismiles Route in Argentina: Definitive Guide: Explore the trans-Andean side from Fiambalá, Catamarca.