Spas with reservation required in California

San Francisco, California

Adults-only Russian bathhouse in San Francisco's India Basin with steam rooms, cold plunge, rooftop deck and a café, open daily except Tuesday.

Palm Springs, California

Adults-only hot springs resort on Miracle Hill in Desert Hot Springs with private mineral tubs, a Finnish sauna, salt room and 35 spa treatments.

Napa Valley, California

A boutique day spa in downtown Napa Valley with nine treatment rooms offering massage, facials and body work, plus sauna, steam and a thermal pool.

Los Angeles, California

A Glendale day spa offering massage, facials, waxing and nail care, plus private jacuzzi-and-sauna suites, open daily 9am to 9pm with walk-ins welcome.

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.

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.

Bishop, California

A century-old natural hot springs pool near Bishop in the Eastern Sierra, with a cooling waterfall, a separate hot soak, and simple day-use facilities.

San Francisco, California

Hotel spa at The Huntington Hotel on Nob Hill with a heated soaking pool, sauna, steam room and terrace, open daily 8am-7pm; treatment booking required.

San Francisco, California

Women-only Korean-style bathhouse and day spa in Japantown, San Francisco, open daily by appointment, clothing-optional.

Sierraville, California

A non-profit hot springs retreat near Lake Tahoe with natural spring pools, reservation-only day and evening soaks, camping and rooms, closed Mondays and

Carmel-by-the-Sea, California

Resort spa at Carmel Valley Ranch with 12 treatment rooms, private terraces, a saltwater pool and infinity hot tub, open to adults by reservation.

Palm Springs, California

Adults-only hotel spa at Tommy Bahama Miramonte in Indian Wells with 15 treatments, eucalyptus steam rooms, a hydrotherapy jacuzzi and saltwater pool.

Calistoga, California

Spa Talisa is the adults-only spa at the Four Seasons Resort Napa Valley in Calistoga, with vineyard-view gardens, barrel saunas and a sunken whirlpool for

Napa Valley, California

Adults-only resort spa built into a wine cave in Napa, with a vineyard-view pool, sauna, steam room and hot tub; reservations required.

San Diego, California

Hotel spa at the historic Hotel del Coronado with an ocean-view pool, 20 treatments, and a seaweed-based signature Ocean Essence Ritual.

Los Angeles, California

Korean-style day spa in Koreatown with detox rooms, body scrubs, gender-specific hours and on-site validated parking.

Los Angeles, California

A Silver Lake day spa with 20 treatments, Thai massage, acupuncture and a salt-infused infrared sauna, open daily 10am-9pm.

Lake Tahoe, California

A 17-room, adults-only hotel spa at Lake Tahoe's Ritz-Carlton with a heated lap pool, sauna and steam room; day pass access requires booking a treatment.

Santa Ynez, California

Adults-only resort spa inside Chumash Casino Resort in Santa Ynez with 21 treatments, a mineral pool, cold plunge and couple's suites.

Napa Valley, California

Adults-only hotel spa in Napa Valley with a co-ed thermal circuit of sauna, steam room and cold shower, open daily 10am–6pm; day passes available.

San Diego, California

Adults-only hotel spa in Carmel Valley with a hydrotherapy circuit, two fireplace lounges, and a $100 day pass covering pools and fitness facilities.

Napa Valley, California

Adults-only hotel spa in downtown Napa with thermal circuits, sauna, steam and cold plunge, plus massages, facials and medical aesthetics.

Calistoga, California

A 20-treatment hotel day spa in Santa Rosa with an indoor caldarium plunge pool, eucalyptus steam rooms, and walk-in or reserved day passes for adults 18+.

Palm Springs, California

A 16-room adults-only hotel in Desert Hot Springs with three natural mineral-water pools fed by a 350-foot geothermal well, plus a small on-site spa and