They are the best on Aconcagua. I have known Rodrigo Mujica for almost 8 years now, and I have climbed both Aconcagua and the Vinson Massif with Adventuras Patagonicas. The guides are excellent, and the whole organization is well organized, especially on Aconcagua which is basically their "home court". Have fun.
Hank Skade, Tiburon CA
