Spas with hot tub

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.

Tucson, Arizona

A hotel spa at an 80-acre Sonoran Desert resort in Tucson, open to overnight guests, with three pools, hot tubs, sauna and yoga classes.

Saturnia, Tuscany

A hotel spa near Terme di Saturnia with an infinity pool, hot tub, rooftop terrace and restaurant, offering day passes for non-guests.

Arima Onsen, Hyogo

Hotel spa in Arima Onsen with Arima's rare iron-rich "ginsen" waters, outdoor baths, sauna and jacuzzi, run as an all-inclusive overnight stay.

New York City, New York

A small Japanese-style bathhouse near Union Square with sauna, hot-tub onsen, cold plunge and a recovery lounge, open by reservation only.

San Diego, California

Hotel spa at Carté Hotel San Diego Downtown with a heated saltwater pool, whirlpool, 28,000 sq ft fitness club with sauna and steam room, open to guests only.

Calistoga, California

A 25-room Sonoma hotel in Forestville with a spa barn offering sauna, steam and pools, mainly for overnight guests.

Asheville, North Carolina

An overnight-stay forest retreat near Fairview with private cedar hot tubs and a shared sauna pavilion session, not a drop-in day spa.

Catskills, New York

Adults-only resort spa in the Catskills with sauna, hot tub, yoga studio and overnight stays for hotel guests only.

Calistoga, California

MoonAcre Spa & Baths is a day spa in Calistoga with a thermal pool, hot tub and sauna, open daily 9am–5pm and geared toward families and couples.

Sedona, Arizona

A boutique resort spa in Sedona with a heated pool, hot tub, yoga and massage, open only to hotel guests.

Palm Springs, California

A hotel-guests-only desert resort in Desert Hot Springs built around natural mineral hot spring pools, with spa treatments and overnight stays.

Philadelphia, Pennsylvania

A private-reservation spa in Philadelphia's Manayunk neighborhood for date nights, birthday and bachelorette parties, with hot tub, sauna and massage chairs

Taos, New Mexico

A moderate-priced day spa at Taos Ski Valley with a heated pool, hot tubs, steam rooms and a day pass open to non-hotel guests.