Nayara Springs, Costa Rica
For over 40 years, Costa Rica’s Arenal Volcano has put on quite a show. Although dormant since 2010, this conical wonder still rises close enough to the Earth’s surface to heat the groundwater and warm the bubbling hot springs. The area is replete with resorts touting opportunities to soak in the mineral-rich waters. Nayara Springs is an intimate luxury oasis.

Located in Arenal Volcano National Park, two anda half to three hours from the international airports, Nayara Springs has 35 dreamy villas surrounded by lush rainforest foliage; some have volcano views. Each structure has high bamboo ceilings and a four-poster, mosquito netting-draped bed. Sliders open to a covered deck with a colorful hammock, a carved wood daybed, and an integrated plunge pool fed by natural mineral hot springs.

Venture beyond your private paradise (and open-air spa) for eco-adventures—ziplining, rappelling, white water rafting, and hiking—along with colorful wildlife such as toucans and tree frogs.

Fairmont Banff Springs, Alberta, Canada
Formerly known as The Banff Springs Hotel, the Fairmont Banff Springs is one of many majestic hotels that William Cornelius Van Horne, president of Canadian Pacific Railway, constructed to attract tourists to Canada. The impetus? Railway employees discovered natural hot springs at the base of Sulphur Mountain.

The iconic resort in Banff National Park has undergone much expansion and renovation since opening in 1888; still, therapeutic waters are key. The 40,000-square-foot spa features three waterfall pools of varying temperatures, an outdoor whirlpool, indoor hot tubs, a eucalyptus steam room, and a grand indoor mineral pool enriched with salts sourced from a lake in South Africa. (Water was piped directly from the hot springs to the hotel until the 1930s, when natural resource protections were enacted.)

To experience the rejuvenating water straight from Sulphur Mountain, there’s Banff Upper Hot Springs, a first-come, first-serve hot spring-fed pool that’s about 10 minutes away by taxi. Walk 10 minutes south of there to ride the Banff Gondola for sweeping views of six mountain ranges.

Dunton Hot Springs, Colorado
In 1885, lured by the natural hot springs, which indicated a mineral-rich environment, gold and silver miners settled on the banks of the West Dolores River, 8,600 feet high in the Colorado Rockies. The site proved too isolated; within 35 years, it was abandoned. Fast forward to 2001, when the ghost-town-turned-dude-ranch was reimagined as Dunton Hot Springs, an all-inclusive resort.

Here in the San Juan Mountains, 14 restored mining-era log cabins, each with distinctive Americana décor, encircle a chef-driven saloon where Butch Cassidy once stopped after robbing a bank in Telluride. Guests can soak in calcium bicarbonate-rich geothermal water in a rustic 19th-century bathhouse, an outdoor clay-rimmed pool, at the source itself (slip in under the stars), and in other spots with meadow and mountain views.

Between soaks and alpine-inspired spa treatments, there’s snowshoeing, cross-country skiing, fly fishing, horseback riding, mountain biking, and more. This is wilderness country, so be on the lookout for bears, cougars, and bald eagles.

Blue Lagoon, Iceland
In Iceland, warm soaks are a way of life. Blue Lagoon, perhaps the country’s most well-known geothermal spa, was discovered unintentionally. In 1976, runoff from a geothermal power plant formed a milky blue reservoir when the ground made of porous volcanic rock ground failed to absorb the water.

Today, the Blue Lagoon sits on a field of black lava 45 minutes from Reykjavik. Many visitors stop on the way to or from the airport to experience the healing waters, whose primary elements are silica, algae, and minerals. Entrance includes a silica mud mask and drinks from the in-water bar, or you can reserve a five-hour spa pass and luxuriate in the grotto-like steam room and sauna.

Better yet, make Blue Lagoon a home base. There are two hotels on the property: the Nordic-style Silica Hotel and the luxurious and intimate Retreat at Blue Lagoon. The latter offers modern and sophisticated suites with unlimited access to the spa and a more secluded and enchanting lagoon.

Amanemu, Japan
Japan is a mountainous country with numerous active volcanoes and thousands of hot spring sources. Bathing culture reaches back thousands of years here, and onsen (establishments with mineralized hot springs baths) are commonly used as health retreats. Amanemu infuses absolute luxury into that tradition.

Nestled into the forested hills of Ise-Shima National Park, Amanemu draws inspiration from ryokan, traditional Japanese inns with communal baths. The resort’s guest quarters—28 freestanding blackened wood structures with pale wood interiors—are contemporary odes to ryokan architecture. Each suite and villa features its own mineral-rich private onsen and lavish verandas for indoor/outdoor living.

The property’s spa delights with a large outdoor thermal spring in a modern garden setting. The facility has two private onsen bathing pavilions and offers treatments combining restorative waters with Kampo therapy, an herb-based healing practice that combines local and seasonal ingredients such as pearl powder and seaweed. There is also an infinity pool overlooking Ago Bay.