Having had a few days in which to acclimate to the high altitude, as well as getting in shape by hiking, we went for a fairly strenuous hike in the South Mineral area. This one was to the Ice Lakes basin, a climb from 9600 to 12,600 feet on a 3.5 mile switchback trail. Peri seemed unaffected by the altitude, but did get a bit impatient with how slowly we humans sometimes progressed.