Spas with reservation required

Kapaau, Hawaii

An oceanfront eco-boutique hotel and wellness retreat on Hawaii Island's North Kohala coast, open to overnight guests only, not day visitors.

North Royalton, Ohio

A North Royalton day spa built around a salt room and sauna, with adults-only halotherapy sessions on a walk-in or reserved basis.

Albuquerque, New Mexico

Hotel Zazz is an adults-only boutique hotel in Albuquerque's Nob Hill district with an on-site spa, heated pool and speakeasy lounge.

Austin, Texas

Adults-only resort spa on Lake Austin offering all-inclusive overnight stays and limited day passes to pools, saunas, steam rooms and lake activities.

Koh Samui, Surat Thani

A day spa in Bo Phut, Koh Samui, open daily 9am to 11pm with a sauna and traditional Thai treatments for solo visitors and couples.

Minneapolis, Minnesota

A Northeast Minneapolis wellness studio rooted in Traditional Chinese Medicine, offering sauna access by reservation in the Bottineau neighborhood.

Las Vegas, Nevada

Float tank, massage and salt therapy spot in Peccole Ranch, Las Vegas, open daily with walk-ins accepted alongside bookings.

Dobbs Ferry, New York

A Dobbs Ferry day spa with a hydrotherapy circuit, relaxation lounge, massages and facials, open daily with reservations recommended.

Ojai, California

A small, independently owned day spa in Ojai offering facials, massage, head spa treatments, infrared sauna and salt therapy.

Park City, Utah

A sauna-and-cold-plunge day spa in Park City with memberships, private group buyouts, and reservation-only access.

Nashville, Tennessee

A Gulch studio for infrared sauna and cold plunge sessions in private suites, open daily with reservations required.

Los Angeles, California

A wellness retreat in Westlake's Wilshire corridor offering cold plunge, sauna and movement classes, built around group and community sessions.

Aachen, North Rhine-Westphalia

Adults-only day spa in Aachen with a hydrotherapy circuit and relaxation lounge, open daily 10am–9pm, upscale pricing.

The Hamptons, New York

Adults-only destination spa and 12-room retreat in Water Mill, offering hydrotherapy, yoga, spa treatments and overnight stays by reservation.

Houston, Texas

A moderate-priced day spa on the 23rd floor of a downtown Houston office tower, open Wednesday through Sunday with a relaxation lounge and sauna.

Carmel-by-the-Sea, California

A hotel spa inside Carmel-by-the-Sea's Hyatt Regency Monterey property, with hydrotherapy, sauna and a relaxation lounge for guests and couples.

Naples, Florida

A hotel spa inside the Inn on Fifth in downtown Naples, open daily for massages, facials, nail services, sauna, steam room and lounge access.

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.

Boston, Massachusetts

Day spa in East Boston offering massages, facials, body care and a hydrotherapy circuit, open daily except Sunday with walk-ins welcome.

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

A moderate-priced day spa inside The Crescent complex in Oak Lawn, Dallas, with a sauna and both walk-in and reservation options.

Bad Ragaz, St. Gallen

A resort thermal spa in Bad Ragaz with indoor and outdoor thermal pools and sauna, open daily 7:30am–8pm, reservation required for day passes.

Palm Beach, Florida

A budget-friendly day spa in Palm Beach Gardens offering massage, facials and a private hot-cold contrast therapy suite, with walk-in access.

Tepoztlán, Morelos

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