A small river canyon located 7km past the town of Socaire with many good bolted routes and also trad options. The the canyon runs approx. east-west where the climbing area is, but shade can usually be found around a corner. The rock is decent, but there are still some routes that are still being cleaned and have flaky, loose rock. The altitude of the location makes the climbing a bit different in terms of intensity, but overall a really cool place to climb (especially sport).
Camping can be done right in the bottom of the canyon and there is a good running water source no more than 50m North of the rim of the canyon. Hang any food you might have off of a bolt because there are plenty of little mice that will get into your food at night.
From San Pedro de Atacama (buses go here from everywhere in the area):
Take a bus south towards Toconao (trad climbing here) and get off near the main square. Here you will need to talk to the locals to see if they know of anyone who is/will go to Socaire. There are several people in town that are willing to drive you south for a small fee, it's just a matter of being persistent.
Once on your way to Socaire, continue through the town for another 7km. You should pass over a small river canyon called the Quebrada de Nacimiento. No more than 200m after you go across the canyon you should stop and hike down into the canyon. Hike to the west in the bottom of the canyon and you will begin to see bolt lines, a little further and you will come across a perfect place to camp.
Hike back up to the road and hitchhike. All roads lead back to San Pedro and many people go south to see the Miscanti Lagoons. You should not have much trouble finding a ride back, especially if you are returning on a weekend.
Warning: Although everyone will tell you there is a bus that goes to Socaire, as of Oct. 2012, all of those services had been cancelled to lack of demand.