Iron Mountain Hot Springs

Instead of one giant tank, Iron Mountain spreads its water across dozens of small soaking pools strung along the Colorado River on the west side of Glenwood Springs, so you can move from a mild 89°F pool to a 108°F one in a few steps and pick the heat that suits you. The resort counts 35 pools in all, plus a Sauna Summit with plunge pools and two specialty pools enriched with magnesium and potassium. Two ticket tiers shape the visit.

Select Access, roughly 43 to 75 USD depending on the date, covers the family-friendly areas, including a family mineral pool and jetted spa. Premier Access, about 75 to 150 USD, opens the adults-only zones for guests 21 and over with ID, among them the WorldSprings pools, the Sauna Summit and the Sandbar Café. Children under five stay in the family zone and cannot use the geothermal pools.

Hours are 9 am to 10 pm daily, with a handful of holiday and maintenance closures each year. The complex sits under a mile from the Glenwood Hot Springs Pool, so you can try both styles in one trip, though there is no lodging on site. The downside is cost and complexity: the tiered pricing takes some decoding, and a peak-day Premier pass can reach 150 USD per person.