The southern route on Cerro Toco is an easy 2-3 hours hike up a path over scree and maybe patches of snow. You can drive up to an elevation of 5000 meters which will leave a difference of only about 600 meters to the summit of Cerro Toco. Mind that if you do this as a day hike from San Pedro, you´ll drive up 2500 meters in less than an hour! Obviously you need to be well acclimatized to this elevation.
The trailhead of the southern route on Cerro Toco is located at an old sulfur mining camp, about 50 kilometers from San Pedro. The road is a little bumpy in places but the trailhead seams reachable in a normal passenger car.
As you leave San Pedro de Atacama toward Bolivia and Argentina, you pass the chilean boarder guard. Since you won´t leave Chile when climing Cerro Toco on this route, you don´t need to get your passport stamped here. Our driver just drove around the back side of the building without even stopping.
100 meters or so behind the border guard there is the turnoff toward Bolivia and Chile (CH-27). Follow this road for about 40 kilometers as it climbs steeply for over 2000 meters! Near the 40 km distance marker you´ll see a big sign that says "Acceso Bolivia a 500m" (500 meters from the turnoff to Bolivia obviously). About 50 meters ahead of the sign is the turnoff toward the old mining camp.
Follow the dirt road as it climbs up toward the south side of Cerro Toco. At the first fork turn right (the left branch seems to just return to the main road). After a short while you´ll hit another junction. Turn left here. This is the road that leads up to the old mining camp. You´ll know that you´re on the right track when you see all the white and yellow blocs of sulfur that litter the sides of the road.
Follow this road until you see the old mining camp on the left side of the road at an altitude of about 5000 meters (see this picture
). This will be about 9 kilometers from the turnoff at CH-27, about an hours drive from San Pedro. Park you car here.
If you don´t have your own car, Volcano Expediciones in San Pedro will give you a lift to this place for 45´000 pesos a car load. Alternatively you may be able to hitch a ride on one of the buses that leave San Pedro towards Bolivia and Argentina and just have them drop you at the 40 km marker. This will add another 1000 meters elevation gain to your hike though!
From the old mining camp follow the road for another 200 meters or so. On the left handside you will discover a valley with a path zigzaging up it´s right handside slope (see this picture
). Simply follow the path for about 1 1/2 hours (depending on your level of acclimation of course) until you reach a flatter part below the summit. You´ll see the path follow steeply the right handside of the last hill to the summit. If there is snow, this part may be icy as it doesn´t get much sunshine for most of the day. If that is the case, it may be easier to follow the valley as it goes around the left handside of the hill to a little pass, a mere 50 meters or so to the east of the summit. About two to three hours from the old mining camp.
Go back the same way.
Sturdy hiking boots. Ski poles are helpful.