FOUND! And, man oh man, was this the hardest cache I've ever had to get to. Second cache in Peru.
I found this cache while on the 5day/4night Salktantay trek with my two good friends (not geocachers), 9 other awesome fellow trekkers, and our fabulous guide Elias (go team Puma)! Our ascent of the pass was only our second day trekking, and I think it was probably the hardest climb I've ever done, purely because of the elevation. Luckily, the headaches went away over the course of the day, and by the time we reached Salkantay Pampa (15,100 feet) at 8 or 9am, I was feeling much better. We took the obligatory group, solo, and group combination photos at pretty much every spot at the top, before doing the short hike to the nearby alpine lake. On the way I made everyone stop to find this cache with me. I may not have gotten 11 new geocaching converts, but hopefully at least one. I went straight to the coordinates where the cache was because I was holding everyone up, and after a quick circumnavigation of the boulder, I noticed the right things and found the cache pretty quickly. Left an HQ tag of some sort (can't remember which) in the cache.
What an amazing experience the trek was. The following 3 days just got better and better. Descending into the jungle below the pass was probably the most beautiful part of it for me.
Thanks for placing a cache up here! It was in decent condition and the logbook was dry.