Spas with reservation required

Nashville, Tennessee

Upscale day spa in Franklin outside Nashville offering facials, massages, a salt room, infrared sauna and hydrotherapy tub, open daily by reservation.

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.

Soufrière

Hotel spa at Ladera on the Pitons ridge in Soufrière, with day passes, couples treatments and volcanic mineral pool access.

Minneapolis, Minnesota

A St. Paul wellness studio in Macalester-Groveland offering infrared sauna, float tanks, salt therapy and cold plunge by reservation, adults-only, day-pass

Carefree, Arizona

A 20-plus-acre desert wellness resort in Carefree, Arizona, with a full spa, pools, and 100-plus weekly fitness and mindfulness classes open to day visitors by

San Diego, California

A La Jolla medical spa specializing in lymphatic drainage, colon hydrotherapy and detox treatments, open since 1993, adults only, by reservation.

Chicago, Illinois

Upscale day spa in Lincoln Park, Chicago, where booking any treatment unlocks all-day access to a hydrotherapy circuit, thermal suite and outdoor terrace.

Tucson, Arizona

A resort day spa at Westward Look in Tucson with a thermal pool, sauna, steam room and cold plunge, open daily 9am-6pm by reservation.

Washington, D.C., District of Columbia

Hotel spa at Pendry Washington DC - The Wharf with eucalyptus steam rooms, a heated whirlpool and an outdoor terrace pool, open daily 10am-6pm.

Philadelphia, Pennsylvania

Hotel spa on the third floor of The Rittenhouse overlooking Rittenhouse Square, with massage, facials, body treatments and a salon.

Orlando, Florida

Hotel spa at the Rosen Centre on International Drive in Orlando, offering massages, facials, nail care and access to a steam room, pool and fitness center.

Palm Springs, California

Downtown Palm Springs day spa built around a natural hot mineral spring, with private mineral baths, sauna, steam room and massage.

Asheville, North Carolina

A day spa in a converted barn on Horse Shoe Farm near Asheville, offering massage and body treatments amid farm and mountain surroundings.

Hudson Valley, New York

Hotel spa inside The Abbey Inn in Peekskill, overlooking the Hudson River, with six treatments including a Japanese head-and-foot package.

Dublin, Leinster

An outdoor barrel sauna and cold plunge pool setup in Saggart, Dublin, booked in 50-minute sessions for groups and couples.

New York City, New York

Thermal bath circuit and massages in a restored 1883 Tribeca textile factory, with a skylit tepidarium and candlelit thermal pools; reservation required.

Rishikesh, Uttarakhand

An upscale riverside resort 18 km outside Rishikesh with an in-house spa, yoga studio and restaurant, open only to overnight guests by reservation.

Scottsdale, Arizona

Hammam-inspired hotel spa at Omni Scottsdale Resort & Spa at Montelucia in Paradise Valley, with private suites and massage, facial and body treatments for

Mariánské Lázně, Karlovy Vary Region

Hotel spa inside Mariánské Lázně's Ensana resort complex, open daily 8am–5pm for guests with reservations.

Asheville, North Carolina

Ayurvedic destination retreat in the Blue Ridge Mountains near Asheville, with day-pass spa visits and multi-night panchakarma cleanses by reservation.

Charlotte, North Carolina

A moderate-priced day spa in Charlotte's SouthPark area with a sauna, steam room and thermal pool alongside massage, facial and body-treatment menus.

Evian-les-Bains, Auvergne-Rhône-Alpes

A Hilton hotel spa on Lake Geneva's shore in Évian-les-Bains, open to day-pass visitors by reservation.

Key West, Florida

A hotel spa at Pier House Resort in Key West for guests only, offering couples treatments for ages 14 and up with advance reservations.