Glenwood Springs, Colorado, has several fine hot spring options, but if you want to get away from the highway and soak in undeveloped spring pools, look for South Canyon Hot Springs. Just a few miles west of town and totally free, it attracts a diverse group of hippies, local workers, and through travelers. The waters are between 105 and 99, depending on how close to the source you park yourself. The trail can be muddy or snow-packed, but it’s less than a quarter mile long and the reward is well worth it.