Spas with reservation required

Hong Kong

Hotel spa on the 41st floor of the Cordis in Mong Kok, with a day pass covering pool, sauna, steam room and onsen shower for HK$500.

Miami, Florida

Hotel spa inside Dua Miami, Autograph Collection in Brickell, open daily 9am-6pm, with sauna, steam room, cold plunge and couples massage rooms.

Hot Springs, Arkansas

Day spa and Aveda salon in Hot Springs with baths, a salt room, oxygen bar and massage, facial and hair services.

Durango, Colorado

A hot springs resort in the Animas Valley near Durango, Colorado, with 32 mineral pools, cold plunges, a lap pool and private cedar soaking tubs.

Las Vegas, Nevada

Hotel spa inside Hilton Grand Vacations on the Las Vegas Strip, open to non-guests via day pass or booked treatment, minimum age 16.

Palm Springs, California

Moroccan-themed inn in Desert Hot Springs with natural mineral hot springs, a spring-fed pool and day-pass access from 9am to 4pm.

Charleston, South Carolina

A West Ashley day spa in Charleston offering lymphatic massage, infrared sauna, halo therapy and foot soaks by reservation, no day pass.

Palm Springs, California

Hotel spa inside the Avalon in Palm Springs, open Thursday through Monday, with a $75 day pass covering jacuzzi, sauna, cold plunge and steam rooms.

Kraków, Lesser Poland

A private spa near Kraków that's booked out entirely for one couple or group at a time, with jacuzzi, two saunas and a salt inhalation tower.

Scottsdale, Arizona

Day spa in South Scottsdale focused on facials and a signature holistic massage, with sauna, steam room, thermal pool and cold plunge on site.

Monroe, New Jersey

Affordable day spa in Williamstown, NJ with sauna, steam room and thermal pool, offering massages, facials and couples treatments.

Columbia, Maryland

A luxury medical and day spa in Columbia's Town Center combining facials, massage and laser/injectable treatments with a thermal pool, sauna and steam room.

Vail, Colorado

A small massage and facial spa on the second floor of the Solaris building in Vail, offering nine treatments with no day pass.

Denver, Colorado

A medical spa in Thornton offering Japanese head spa treatments, body wraps, chemical peels and B12 shots, with sauna, steam room and pool access.

Orlando, Florida

Medical spa in Orlando offering facials, massage, body contouring and couples packages, with an on-site sauna, steam room and thermal pool.

New York City, New York

A below-street-level day spa in NoHo with thermal baths, a three-story indoor waterfall, sauna, steam room and cold plunge, plus massage and facial treatments.

Boston, Massachusetts

A reservation-only day spa in Revere, near Boston, with sauna, couples suite and tropical rain vichy shower treatments.

Bormio, Lombardy

Adults-only hotel spa near Bormio with thermal pools, a relaxation lounge and a 13-treatment menu; day passes start around €44 for evening entry.

Los Angeles, California

A women-focused Korean day spa in Pico-Union with steam, salt and ice rooms, open daily 9am to 9pm, with massage and facials open to men too.

Williamstown, Massachusetts

Day spa in a converted 1762 grist mill on the Green River in Williamstown, offering massage, facials and a private outdoor hot tub.

Scottsdale, Arizona

A moderately priced day spa in South Scottsdale with lake-view suites, massage and facials, plus a dedicated couples treatment room.

Miami, Florida

A Peruvian-themed day spa inside the Victor Hotel on Ocean Drive, South Beach, with a hamam, steam room, sauna and a couples suite.

Oslo

Waterfront sauna spot on Aker Brygge with shared and private saunas, sea bathing, and sauna boat trips on the fjord.

Bursa

A historic thermal bathhouse and small hotel in Bursa's Kükürtlü district, with separate men's and women's hamams, day passes, and overnight stays.