Spas with solo travelers

Park City, Utah

A walk-in sauna-and-cold-plunge studio in Park City with a 198°F cedar sauna, 40° and 50°F plunge pools, and $39 day passes.

Scottsdale, Arizona

Hotel spa at the Inn at Eagle Mountain in Fountain Hills with sauna, steam room, pools and a $69 60-minute massage as its signature treatment.

Sayulita, Nayarit

A hillside boutique hotel spa outside Sayulita with sauna, steam room, cold plunge and ocean-view pool, open on a day-pass basis.