Spas with reservation required

Rogaška Slatina, Savinjska

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

Miami, Florida

Hotel spa at The Setai in Miami Beach with 7 ocean-view treatment rooms, 5 couples suites, saunas, steam and a cold plunge.

Gold Coast, Queensland

A 90-minute hydrotherapy circuit in Southport with a Finnish rock sauna, 5° ice baths and hot/cold magnesium pools, day pass $49.

Palo Alto, California

A Palo Alto day spa built around private hot tub and cold plunge suites, with about 50 treatments and couples options, open daily by reservation.

Scottsdale, Arizona

Adults-only hotel spa at the Fairmont Scottsdale Princess with a rooftop pool, grotto waterfall pool, sauna, steam room and cold plunge, open daily 6am-7pm.

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.

Charleston, South Carolina

Adults-only luxury day spa in Charleston's Westside offering 42 treatments and a $370 signature package, with reservations required and no walk-in day passes.

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.

New York City, New York

Midtown Manhattan day spa with 13 treatments, a jacuzzi and package deals for couples, birthdays and bachelorette groups.

New York City, New York

A Midtown East day spa in Manhattan offering massages, facials, mani-pedis, a hot tub lounge and package deals for couples, birthdays and bachelorette groups.

Dallas, Texas

Hotel ZaZa's spa in Oak Lawn offers massage and skincare treatments with valet parking and pool access, but no standalone day pass.

Luhačovice, Zlín Region

A destination spa in Luhačovice built around mineral springs, offering medical cures, sauna world, outdoor whirlpools and fitness, open daily 7am–8pm.

Vail, Colorado

Hotel spa inside Park Hyatt Beaver Creek with a 5-step hydrotherapy circuit, sauna, steam room and day-pass access to massages, facials and fitness classes.

New York City, New York

Luxury hotel spa inside the Lotte New York Palace on Madison Avenue, offering ila's organic treatments, sauna, steam room and private yoga studio.

Austin, Texas

Day spa and medspa inside The Loren Hotel by Lady Bird Lake, open to both hotel guests and the public, with massage, facials and injectables.

Wulai, New Taipei

A hilltop Wulai B&B with sodium bicarbonate hot-spring baths in every room and an outdoor infinity pool, geared toward couples.

Dallas, Texas

An Ayurvedic clinic in Dallas offering consultations, panchakarma packages and individual therapies, by appointment only.

Los Angeles, California

Day spa in Woodland Hills with a hydrotherapy circuit, massage, facial and body treatment menu, open daily 8am-10pm (closed Tuesdays).

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

Day spa in San Diego's Hillcrest neighborhood offering steam room, dry sauna and jacuzzi, open seven days with free parking nearby.

Wilton Manors, Florida

A day spa in Wilton Manors near Fort Lauderdale offering massage, bodywork and organic skincare, with couples treatments and reservation-based booking.

San Diego, California

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