Spas with upscale

Bagno Vignoni, Tuscany

Hotel spa in a 15th-century Bagno Vignoni palazzo with a thermal pool fed by the village's natural hot springs, open to day visitors.

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.

Santa Fe, New Mexico

A 77-acre hot springs resort outside Santa Fe with spring-fed thermal pools, day-pass soaking packages from $175, and overnight lodging.

Shibu Onsen, Nagano

Reservation-only private hot spring and sauna suites at a Nagano brewery complex, built around a craft beer bathing plan for two to four guests.

Rotorua, Bay of Plenty

A Rotorua day spa built around Ngāti Whakaue hot-springs traditions, centered on a seven-step geothermal Restorative Journey with lakeview thermal pools, mud

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.

Calistoga, California

A 1952 Calistoga hot springs resort with three mineral pools at 85, 95 and 104°F, mud baths, overnight rooms and a day-pass option.

Palm Springs, California

Boutique hotel spa in Desert Hot Springs with two natural mineral hot spring pools, day passes, and overnight rooms that include breakfast.

Ojo Caliente, New Mexico

Historic New Mexico hot springs resort with communal mineral pools, private tubs, and day-pass soaking near Taos.

Puyehue, Los Lagos

A forest resort spa in Puyehue, Chile, with volcanic thermal pools and outdoor baths, open only to hotel guests.

Portland, Oregon

Adults-only hotel and thermal springs on NE Alberta St in Portland, with vitality pools, a day-pass option, and spa treatments.

Shibu Onsen, Nagano

A ryokan in Shibu Onsen with indoor and outdoor hot-spring baths fed by two blended mineral springs, open only to overnight guests.

Tyrol, Bavaria

Hotel spa in Kreuth-Reitrain near Tegernsee with a 3,000 sqm onsen-style bathing area, hot and cold pools, saltwater pools and sauna, open on a day-pass basis.

Palm Springs, California

A resort spa in Desert Hot Springs, near Palm Springs, built around natural hot mineral pools, open daily from 8am to 9pm for day-pass visitors and hotel

Ibusuki, Kagoshima

A ryokan-style hotel in Ibusuki with source hot-spring baths, both shared and private, open only to overnight 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.

Afyonkarahisar

Resort hotel in Afyonkarahisar built around thermal pools, spa treatments and physical therapy, open to hotel guests.

Atami, Shizuoka

A hotel spa in Atami with a thermal onsen pool, open only to overnight guests staying at Fufu Atami.

Yufuin, Oita

A small hillside ryokan near Yufuin's town center where every room has its own half-open-air bath filled with 100% source hot-spring water and a view of Mt.