High-Altitude Health Warning -- What's true for San Pedro is even truer in Putre and beyond: The altitude here will slow you down, and it's tougher to deal with because at 3,500m (11,500 ft.), Putre is a quarter of a mile higher up from San Pedro. It's even higher than Cuzco in Peru, and Lake Chungará is one of the world's highest bodies of water and much higher still at 4,500m (14,760 ft.). Take it easy; even the young and the fit have fallen gravely ill after overexerting themselves. Consult your doctor before heading here if you have a heart or lung condition, and book only tours that carry emergency oxygen equipment. (Putre only has a small clinic.) Headaches and nausea are common occurrences at first; drink plenty of water and have some coca tea to help you adjust. Yes, it's perfectly legal; and no, you won't become a drug addict.