Spas with moderate

Denver, Colorado

A 6,000-square-foot hotel spa in downtown Denver's Granite Tower, open to day-pass visitors 18 and older for $40 to $75.

New York City, New York

Korean jjimjilbang-style spa in Manhattan with saunas, steam room, soaking tub and body scrubs, open daily 8am-11:30pm on a day-pass basis.

Denver, Colorado

A hotel spa in downtown Denver with a $150 day pass covering pool, steam room, whirlpool and fitness centre access, open to non-guests.

Las Vegas, Nevada

Hotel spa on the Palms casino level in Las Vegas with steam rooms, saunas, a seasonal pool and 32 treatments including massage, facials and body work.

Dallas, Texas

A day spa in Lower Greenville with a $99 custom facial or Swedish massage, couples treatments, valet parking, and a minimum age of 18.

Ho Chi Minh City

A Korean-style jjim jil bang in Ho Chi Minh City with six heated rooms, a Dead Sea mineral soaking pool, and massage, hair-wash and facial services.

Aspen, Colorado

Adults-only hotel spa at Viewline Resort Snowmass with a $25 day pass, steam rooms, outdoor pool and whirlpool, reservations required.

Atlanta, Georgia

Day spa and fitness studio in Historic College Park, Atlanta, combining a signature massage menu with Barre, Yoga, HIIT and a self-regulating sauna.

Whistler, British Columbia

Hotel spa at the Westin in Whistler Village with 19 treatments, couples massage, and free access to the hotel's pools, sauna, steam room and gym.

Spa, Liège

Thermal baths in the town of Spa, Belgium, fed by natural mineral water, with saunas, hammams and separate textile and naturist relaxation areas.

Rogaška Slatina, Savinjska

Wellness center at Grand Hotel Rogaška in Rogaška Slatina, Slovenia, with pools, saunas and fitness; day pass available by reservation.

Hanoi

Day spa in Hanoi's Old Quarter with a herbal steam room, Himalayan salt stone room and jacuzzi, open daily 10am–10pm.

Los Angeles, California

Day spa in West Hollywood with wet and dry banyas, pool, sauna, cold plunge and café; day pass is $110, walk-ins welcome.

Auckland

A family-run rainforest resort in the Waitakere Ranges near Auckland offering a day spa, private yoga and free hiking and biking trails.

Santa Fe, New Mexico

A 16,000-square-foot adults-only hotel spa at Hilton Buffalo Thunder near Santa Fe, with separate men's and women's saunas, steam rooms and whirlpools.

Catskills, New York

A day spa on 3 wooded acres in Woodstock, NY, with massage, skin care, a steam room, sauna and small gym, open daily except Wednesday.

New York City, New York

A Brooklyn bathhouse built around the largest banya in the US, with Turkish and Moroccan hammams, multiple saunas and a hydrotherapy pool circuit.

The Colony, Texas

A day-soaking spa in The Colony with mineral pools at varying temperatures, seven saunas, cold plunges and a poolside café.

Glenwood Springs, Colorado

A natural geothermal vapor cave in Glenwood Springs, Colorado, where visitors steam in ancient rock chambers and add massages, mineral baths or body treatments.

San Diego, California

Korean-style day spa in Kearny Mesa with red clay and salt saunas, hot and cold tubs, an ice room, and walk-in day passes.

Sun Valley, Idaho

A 50,000-square-foot health club and spa in Ketchum with saltwater pools, a full gym and massage, facial and other spa treatments.

Palm Springs, California

Adults-only clothing-optional resort in Desert Hot Springs with mineral water pools, whirlpools, a nude cedar sauna and day-pass access.

Águas de São Pedro, São Paulo

Day spa in central Águas de São Pedro offering massage, facials and couples packages, open daily except Sunday with walk-ins and day passes welcome.

Calistoga, California

A day spa and co-ed bathhouse in downtown Sebastopol with women-only and clothing-optional sessions on set days.