Spas with reservation required

Chicago, Illinois

A Gold Coast medical and day spa combining massage, facials, laser and injectables with a robe-and-locker relaxation lounge, open daily except Tuesday and

Tepoztlán, Morelos

A day spa and temazcal (traditional Mexican sweat lodge) in Tepoztlán, Morelos, open Wednesday through Sunday with reservations suggested.

Park City, Utah

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

Berkshires, Massachusetts

A Great Barrington wellness studio focused on detox therapies like colon hydrotherapy, infrared sauna and liver flushes, by appointment only.

Tucson, Arizona

Adults-only day spa in Tucson's Triangle area offering lymphatic facials, dermaplaning and a hydrotherapy circuit; reservations required.

Hudson Valley, New York

An outdoor spa on the Hudson River in Kingston, NY, with two waterfront barrel saunas and garden massage cabins, reservation required.

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.

New York City, New York

A small Japanese-style bathhouse near Union Square with sauna, hot-tub onsen, cold plunge and a recovery lounge, open by reservation only.

Prague

A beer-spa and wellness venue in Prague's Nové Město district offering beer-bath tubs, massages, and a saunarium, open daily from 11am to 11pm.

Taos, New Mexico

A boutique skin and body studio in Taos offering facials, lymphatic massage, Endermologie and head spa treatments by appointment.

Catskills, New York

A Catskills retreat center with a Tibetan-style spa offering sauna, steam, pools and cold plunge, built around overnight stays and group programs.

Sedona, Arizona

A 23-casita destination spa resort inside Sedona's Boynton Canyon, open to overnight hotel guests 16 and older for multi-day wellness journeys.

Kyle, Texas

A 88-acre Hill Country resort near Kyle and Wimberley with overnight rooms, a garden spa, pool, hot tubs and day-pass access by reservation.

Seattle, Washington

A downtown Seattle yoga studio with heated and unheated vinyasa, sculpt and hatha classes, plus a sauna, steam room and pools for after class.

Asheville, North Carolina

An overnight-stay forest retreat near Fairview with private cedar hot tubs and a shared sauna pavilion session, not a drop-in day spa.

Penang

An adults-only villa resort spa near Kepala Batas, Penang, with 18 private villas, spa treatments and plant-based dining; reservation required.

Scarborough

A boutique hillside hotel above Bacolet Bay in Scarborough, Tobago, with an infinity pool and ocean views, built around a converted 150-year-old Donkey Cart

Naples, Florida

A resort spa at the Hyatt Regency Coconut Point in Bonita Springs, open to hotel guests by reservation, with pool access on site.

Calistoga, California

MoonAcre Spa & Baths is a day spa in Calistoga with a thermal pool, hot tub and sauna, open daily 9am–5pm and geared toward families and couples.

Tampere, Pirkanmaa

A budget-friendly public sauna and bathhouse in Tampere, open to walk-ins but reservations are also an option.

Houston, Texas

A women-owned day spa in South Central Houston offering massages, facials and laser treatments alongside a sauna and oxygen lounge.

Denver, Colorado

Private Russian banya spa in Denver's Cheesman Park offering banya sessions, massage and body treatments by appointment since 1995.

Big Sur, California

Adults-only hotel spa at Ventana Big Sur with ocean-view treatment rooms, outdoor cabanas for couples, and a 24-hour fitness and yoga space.

Philadelphia, Pennsylvania

A private-reservation spa in Philadelphia's Manayunk neighborhood for date nights, birthday and bachelorette parties, with hot tub, sauna and massage chairs