Cerro Tomasamil is a highly eroded dormant volcano, on the edge of the Atacama Desert in southwestern Bolivia. Its complex array of ridges and the slopes in between consist mainly of broken talus and scree. More solid rock might be found along the crest of some of the ridges. This area of the Cordillera Occidental is packed full of old volcanoes, clustered closely together. Many of them are in the 18,000 to 20,000 foot range and quite prominent, with Tomasamils prominence being just over 5200 feet. Spread out between these giants, are a series of salt flats, which may give the valley floor a shimmering white appearance. Historically, during the winter and spring Tomasamil and the surrounding peaks were snow capped but in recent years the usual precipitation has ceased. Wild game trails can be found leading up to what was once a water source. It's yet to be seen if the snows of Tomasamil will return.
On the lower slopes of Tomasamil you might see a wild vicuña or encounter the occasional yareta plant. Large communal piles of dung on the western slopes suggest that vicuñas favor this area. In any case, if you decide to climb Tomasamil, you will likely be the only one doing so. I have heard it estimated that this peak has seen less than twenty ascents. There are a number of reasons for this. Peakbagging has not exactly caught on in local Bolivian culture and anyone traveling to this area from abroad has an abundance of other volcanoes to choose from. Also, access to the base of the mountain is not exactly straight-forward.
Unlike some of the neighboring peaks, on Tomasamil there are no old mining roads leading up onto its slopes. To climb to the summit one must undergo considerable mileage and elevation gain. There's also the matter acclimatization. It's important that one has prepared their body for approaching the 20,000 foot mark. Premature exposure to these altitudes can prove fatal. It is suggested that prospective climbers visit a few lower peaks in the days preceding a Tomasamil climb to allow their body time to adjust.
Western ApproachWhether starting at the road or a base camp a bit higher up, the object is to reach one of Tomasamil's ridges. The broad slopes are very loose and only suitable for descent. When I was there, we climbed the northwest ridge but the southwest ridge might also be a good choice and possibly less steep. It all depends on where you start from. Expect to encounter small spiky grass on the lower slopes and loose talus higher up on the ridges. If you do choose the northwest ridge, exercise caution on the steep, loose section around 19,000 feet, which I have nicknamed Red Hill.
Drive southwest on Route 701 for 197 kilometers. Turn right on the unmarked north-south road and drive another 30 kilometers. Cerro Tomasamil will be on your right. If you have an all terrain vehicle, look for the area where there are very few rocks and proceed towards the peak as far as you are able.
From Estación Avaroa:
Drive southeast along the lower slopes of Volcán Ollagüe for 24 kilometers to a junction. Turn north and follow another road for 8.5 kilometers. Cerro Tomasamil will be on your right.