Spas with upscale

Hudson Valley, New York

Resort spa at Mohonk Mountain House with a steam room, sauna and outdoor heated mineral pool, open to overnight guests and day-pass visitors.

Mumbai, Maharashtra

An Ayurveda-based day spa on Marine Drive in Mumbai offering massage, detox and beauty therapies with a relaxation lounge and yoga space.

Dead Sea, Balqa

Resort spa on the Dead Sea shore with 40 treatments, thermal pools, sauna and steam, open to day guests aged 16 and up.

Aspen, Colorado

O2 Aspen is a day spa on South Mill Street offering facials, a yoga studio and a retail boutique, open daily with walk-ins welcome.

Berkshires, Massachusetts

A lakeside resort in Egremont with a seasonal pool and sauna for overnight guests only; no day passes and no spa treatments on offer.

New York City, New York

Adults-only day spa on Governors Island with heated outdoor pools, saunas and an Italian-style café, reachable by ferry from Manhattan.

Scottsdale, Arizona

An adults-only hotel spa in Old Town Scottsdale with sauna, steam room, cold plunge and thermal pools, open to hotel guests 21 and up.

Tyrol, Bavaria

Hotel spa in Kreuth-Reitrain near Tegernsee with a 3,000 sqm onsen-style bathing area, hot and cold pools, saltwater pools and sauna, open on a day-pass basis.

Las Vegas, Nevada

Hotel spa and fitness center at The LINQ in Las Vegas with steam room and sauna, open daily 9am–5pm, day passes available.

Aachen, North Rhine-Westphalia

A suite hotel in central Aachen where each private room has its own jacuzzi and sauna, booked by the night rather than a day pass.

Punta Cana, La Altagracia

Adults-only all-inclusive resort spa in Bávaro with a gym, sauna and couples treatment rooms, open to hotel guests aged 18 and up.

Pagosa Springs, Colorado

A mobile container-trailer spa in Pagosa Springs offering infrared sauna and cold plunge contrast therapy, adults only, by reservation.

Dallas, Texas

Hotel spa inside The Highland Dallas in Lower Greenville, Dallas, with a sauna, steam room, outdoor pool and couples treatment rooms.

Las Vegas, Nevada

A 17,000-square-foot hotel spa in Las Vegas with 15 treatment rooms, a fitness center and a yoga studio, open to Palms guests daily.

Napa Valley, California

Adults-only resort spa in Napa Valley with pools, sauna, steam and a fitness center, open to hotel guests and club members via day pass.

Edinburgh, Scotland

Hotel spa inside The Caledonian on Princes Street with a thermal pool, sauna, steam room and relaxation lounge, open daily 6am to 9pm.

Tucson, Arizona

A hotel spa at an 80-acre Sonoran Desert resort in Tucson, open to overnight guests, with three pools, hot tubs, sauna and yoga classes.

Sedona, Arizona

Hotel spa at Hilton Sedona Resort at Bell Rock offering day passes with a relaxation lounge, steam room, sauna and thermal pool, open daily 6am-8pm.

Park City, Utah

Hotel spa at Mayflower Mountain near Deer Valley with massages, facials, a sauna, relaxation lounge and couples treatments; reservations required.

Scottsdale, Arizona

A hotel spa at Caesars Republic Scottsdale in South Scottsdale with sauna, steam room and pool, open to hotel guests only.

Sedona, Arizona

Hotel spa near Bell Rock in Sedona with sauna, steam room, cold plunge and pools, open to resort guests only.

Los Angeles, California

A hotel spa at Shade Hotel Redondo Beach with sauna, steam, pools, cold plunge and thermal circuits, open to hotel guests overlooking the marina.

Arima Onsen, Hyogo

Hotel spa in Arima Onsen with Arima's rare iron-rich "ginsen" waters, outdoor baths, sauna and jacuzzi, run as an all-inclusive overnight stay.

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.