Aproach
From the trailhead pass the bridge over the Rio Malo to the altitude of 1800 mts, follow the trail that goes into the river canyon towards the south. After 2h of walking along the slope this canyon arrives to a sheppards' hut, this is a summer grazing sector (pasturing sector). The path continues going up the slopes into the canyon. After 3 hours of hiking you will arrive at the foot of the lagoon. Leave the road that you have followed to this point and take the trail that leads to the east of the lagoon's floodgate (damn), continue south until reaching a pass at 2688mts, this separates the valley of the Rio Malo from the sector of the lagoon. Here an old refuge is located, (which probably were left as construction sites of the artificial lagoons) the refuge remains closed. Gaining the pass you will discover the imposing volcano Planchón and one of the lagoons of Teno at your feet. From here continue 2 hours walking along the eastern slopes of the lagoon until you arrive at the foot of the volcano. Camping can be established on the southeastern corner of the lagoon at 2560 mts a spring can be found in this area during the summer. From this last place climb to the ridge towards the south where you will find a trail that takes you to a landmark Planchón (this landmark marks the border between Chile and Argentina). There a great plain begins that crosses the northern slope of the volcano. This plain is also a recommend place to set up camp. It is just on the flat area that forms between the two lagoons and under the "pyramid" (this pyramid forms a shoulder of Planchón), This is at 2690m and after nearly 9 hours of approach altogether.

Ascent
From the base camp, in the foot of the volcano, work toward the south where there is a shoulder of the volcano in the form of a "pyramid". After the snowmelt this becomes a great heap of loose volcanic material. Climb this shoulder, zigzagging to the western edge until reaching the pyramids' summit at 3655mts. From this shoulder follow the ridge (made up of rocks, ice and deposits of volcanic material) that leads to the summit.

There are 1270 mts of altitude gain between the base camp and the summit that can be climbed in 4 hours. Descending by way of snowfields 1 km to the west will take you to the flat area near the base camp.

Peteroa:
The Peteroa Volcano is a pyramidal cone that constitutes the highest point of the Maule Region, with an altitude of 4100 mts. located at the border with Argentina, in which they also call this volcano, Volcan Azufre and forms volcanic complex Planchón- Peteroa, with several craters between the two main summits, Planchón and Peteroa.

In the surrounding area several glaciers exist. They give birth to the Rio Claro that is joined by the Rio Teno in Los Queñes and part of the larger river basin of the Rio Colorado. On the Argentine side, the Rio Valenzuela, that later is transformed into the Rio Grande.

Aproach
From the base camp located at the foot of Planchón you should continue towards the south slope of the mountain about 10 km. arriving at the feet of the volcano by the sector northeast about 3000 mts. After another 2 hours 45 minutes.

Important Note:The times given are approximate depending on the people of the expedition. In summer you must consider allowing for more time.

More Information in:

http://www.andeshandbook.com/