I doubt whether anyone remembers but earlier in the year I wrote that I was going to Peru and that I was a little anxious (to say the least) about how my AF would react to the high altitude. I would like to report that all went well! You are advised to drink lots of water and if you have a guide, the guide will help you to slow down when walking. I kind of forgot this advice one day and consequently spent the evening and night needing to take deep breaths plus my heart was beating a bit faster. My fault! I didn't have any problems climbing the ubiquitous Inca steps - and there were LOTS of them. So, if anyone is thinking of going to Peru with AF, go for it. You'll have the time of your life.