The Santa Cruz trek is, literally, breathtaking. With the highest point at 4,750m, the altitude left me a little breathless and very slow as I struggled uphill. Going downhill was fine, but the direction we trekked in (starting in Cashapampa) meant there was only one section that wasn’t an incline. I was constantly taking layers off and then putting them back on as the temperature fluctuated. At night I alternated between sleeping like a log and shivering wakefulness. It was all totally worth it though.