Peteroa (3603 m /11,821 ft.) &
Azufre (4100 m / 13,451 ft.)

The Sulphur Monsters

V. Peteroa: Trekking
V. Azufre: Alpine
3-4 days

As for rugged beauty, no other mountains in this area can match this group of volcanoes. The massif unfolds along the border east of Curicó over an area of 130 square kilometers. Its highest point is the stratovolcano Azufre at 4100 m which is easily identified from as far away as the Panamericana, given its longish shape and, above all, its icefields - about 60 percent of the volcano is covered by glaciers. Crampons, an iceaxe, and - depending on the route - a rope are essential.

From the Argentinian side, Azufre peak can be climbed in an easy, if slightly boring, long day's tour. The Chilean route, however, will spoil you with views of Chile's second-largest glacier area. It goes past picturesque Laguna Teno; first, up to the impressive craters of 3603 m volcano Peteroa. This monster has erupted as recently as 1991, and its acrid sulphur dioxide and sulphur hydroxide fumes will not let you forget that fact. In one of the craters, you can see caustic sulphuric acid boiling next to the edge of the glacier - a dip is not advisable.

4090 m volcano Planchón rules the northern edge of this massif. Climbing is made difficult on its upper reaches by extremely porous andesite and basalt rock.

This alpine tour is not only worthwhile because of all these peaks; along the route, this tour, whose entire length runs above the treeline, also provides lots of scenic views.

Point of Departure

Curicó.

Approach by Road

Attention: In january 2005, the road to Paso Vergara was closed due to serious damages by landslides. There was no information about when it was going to be reopened. In a vehicle with high clearance, you can only reach the police control at Pichuante, 20 kms. before the border. More information at Carabineros, Comisaría Teno, Ph. +75-411133.

There is a 100 km trip from Curicó on the international road to Vergara-Pass at approx. 2500 m. Public transport only goes as far as Los Queñes resort (km 46), where you will also find the police station. If you want to climb the mountain from the Argentinian side, a Salvoconducto is required, which you will have to get in advance from the Policía de Investigaciones in Curicó since the border patrol office is not connected to the central computer. If your car documents are not in your name, you will need to bring a notarized letter from the owner giving you permission to take the car across the border. The hot springs of Azufre would be a good starting point for the Argentinian route.

Those who choose the Chilean route will only need the usual papers such as passports and car documents. The hot springs of San Pedro, located on verdant green pastures framed by the sides of the Teno valley, are only a few kilometers from the border, and there is camping. For the route described here you can leave your car right by the border marker to start your tour.

Fees

None.

Day 1 (5-6 hrs.)

First of all, while crossing a boggy pasture, you will need to focus on the northernmost point of the volcano Planchón ahead. West of that, you will reach a path that leads directly to the saddle above Laguna Teno; by then, you will have climbed for about an hour and a half. The backdrop behind the glistening blue lake is formed by what is Chile's second largest glacier zone around Cerro Palomo. The slopes stay covered in snow all the way down to the lake until late in the Summer. Some of the snowpack, which can be several meters strong, has broken off and floats as 'iceberg' in the lake.

The path, which is clearly visible at first, starts snaking south towards the peak of Planchón; then, far above the lake, it turns in a westerly direction. Progress is made difficult by steep gorges (quebradas), and it's easy to lose the path on the pasture far below the mountain side. Whatever you do, don't descend into the valley of Río Claro! There are flat places for pitching a tent all along the quebradas. To make it that far, count on another four hours of hiking.

Day 2 (4-6 hrs.)

All the ridges between the quebradas lead uphill towards the summit. Right from the outset, you will be able to spot four characteristic peaks. Choose the ridge leading to the center, and after four hours of tough climbing you will reach the craters of Peteroa. The first one butts right up to the glacier, with sulphuric acid simmering... Don't get too close, the edge is very crumbly! In good weather, southerly and westerly winds will help scatter the toxic fumes of the crater in the background towards the east so that you can approach the edge all the way from the other side.

Walk around the mouth of the volcano to its south, and descend east of the ridge for a few hundred meters in altitude. This is where you can find a makeshift place below the snowline for pitching your tent.

Alternate Option: Climb the highest point of the caldera of Peteroa to the south, round the crumbly summit on ice somewhat below, and continue south down to the saddle between Peteroa and Azufre. From there, Azufre can be climbed on the following day. However, that means spending a night on the glacier, or else a megatour with the ascent and descent on the same day. We suggest you descend immediately if the weather turns bad. Under those conditions, the northerly winds will blow the sulphuric fumes from the crater directly towards you.

Day 3 (ascent of summit: 7 hrs.)

Following the trail from the camp below Peteroa to Azufre you will first get to its glacier. Right beside, a bit further to the left, small waterfalls tumble towards the valley. The entrance to the lower part of the glacier is steep with a 50 degree incline, but that's only for a short stretch. Right above this steep drop-off you will reach an area with huge crevasses. Round the lower part of a rock of several hundred meters' height separating you from the summit to its south. (If you try to circumvent it to the north you will hit an impassable crevasse.) Behind this rock, continue uphill.

The continuation of the route is now easy to see. It will lead over a steep side up to the shallow ridge, and on it, up to the summit proper (4100 m). Depending on the season, you will find high towers of "penitents" which make the passage arduous. Under normal conditions, this ascent will take about four hours.

The descent to today's starting point will take two to three hours. If you want you can descend to the first camp the same day (3-4 hours) and after sleeping there that night, backtrack to the starting point the next day (4-5 hours.)

Alternate route: From the second camp, head north to the east of the volcano complex while staying at the same altitude, cross several quebradas, and after as little as two or three hours, you will spot Laguna Teno. Descending while walking towards it will take you to the trail you know from ascending (about 1 hr.)

For those who want to descend all the way to Argentina and the Termas de Azufre: You will definitely need the Salvoconducto described above, as well as the exit stamp from the Los Queñes police. You will already be partly passing over Argentinian soil while rounding the mountain on the tour described.