Mineral baths, therapeutic mud, volcanic springs—when it comes to hydrotherapy, nobody provides better than Mother Nature. Here’s a roundup of our favorite hot springs experiences, from historic to luxurious to Viking.

Hot Springs National Park, Arkansas

When you think of hot springs destinations, Arkansas may not be first to mind, but in fact, this Midwestern state was one of the first hot springs resort towns, renowned for its bath houses since 1915. Hot Springs National Park actually overlaps with the town of Hot Springs, with the tourist epicenter being Bathhouse Row National Historic Landmark District. Historic Fordyce Bathhouse is closed for renovations till October 2013, but there are other places to try the waters: Buckstaff Bathhouse is more historic, while Quapaw Baths is more upscale.

Calistoga, California

All the way across the country, the Calistoga springs offer similar healing properties, but in a much more developed and luxurious setting. The hotels here tend to have “mineral baths” that are actually swimming pools with mineral spring water piped in; and mud baths safely contained in a custom-designed bath inside the spa. If you prefer luxury over a natural setting, any of the big hot springs spas will suit you, from Calistoga Spa to Solage to Indian Springs.

Carmel, California

Though not often thought of as a mineral springs destination, Monterey County has a few, and it recently debuted a new and sexy hydrotherapy experience. Refuge, billed as “America’s First Co-Ed Relaxation Spa,” features a hot-to-cold hydro thermal cycle. Start in a sauna or steam room, then plunge into a cool pool (or a cold one, if you have the nerve), relax on a lounge chair overlooking Carmel’s scenic mountains...then repeat. Massages are also available for an extra charge.

Saratoga, New York

Legendary for its healing waters long before Europeans discovered the New World, Saratoga Springs continues to draw people from around the world who are curious to test out the springs’ restorative powers. You don’t go swimming in the springs themselves, but the hotels that pipe waters in aren’t exactly luxurious either. The most famous is the Roosevelt Baths at Gideon Putnam Resort. This is where FDR used to go for hydrotherapy, and the setting hasn’t changed much since his day. Patrons recline in individual soaking tubs located in small, simple private rooms, and soak in the effervescent, unnervingly brown water for approximately an hour.

Fairbanks, Alaska

Just outside Fairbanks is Chena Hot Springs, which is the only hot springs pool in Alaska to stay open year-round. And it stays quite busy in the snowy months. It’s always memorable—and many say good for the circulation—to shock your body temperature by alternating extreme hot to cold, whether you do a snow roll followed by a swim, or just relax in the springs and enjoy the cold air outside. Plus, Chena is quite beautiful in every season, but particularly in the winter when icicles and snow banks surround the spring.

Arenal, Costa Rica

Central Costa Rica’s majestic and extremely active volcano is responsible for the volcanic springs that bubble for miles around it...but due credit also must go to local resort developers, who have created some of the most beautiful yet organic-feeling hot springs pools in the world. They range from simple places like Baldi to luxury resorts like Tabacon and The Springs, where the waters are piped into free-form manmade swimming pools. The springs even has a swim-up bar.

St. Lucia

The lush Caribbean island of St. Lucia boasts “the world’s only drive-in volcano.” Whether or not you think that’s advertising propaganda, the volcanic springs around the island are a major tourist attraction. The best-known site is the highly aromatic sulfur springs of Soufriere, but there’s also the mineral baths at Diamond Falls and the spring-fed river waters of Petit Piton.

Banff, Alberta, Canada

High in the Canadian Rockies, nestled within Banff National Park, the Banff Upper Hot Springs have been soothing and warming tired muscles since their discovery in 1884. This is a manmade pool experience, and the simple design hasn’t changed much over the years, but it doesn’t need to. The setting is spectacular and the warm mineral waters are just what one’s body needs after a few days of skiing.

Grindavik, Iceland

No other swimming experience on earth can compare to the Blue Lagoon for dramatic beauty and strangeness. This natural-formed lagoon is so large you can get lost in it—even though there are usually busloads of people there, the lagoon monitors warn you not to drift too far away from the shore. The water steams into a thick mist and the Icelandic wind blows icily around your head, while your toes barely graze the rough natural rock below. Slather yourself in therapeutic mud, book a treatment in the spa area off to one side, or float over to the booze booth and grab a beer to sip in the shallows.

Beppu, Japan

The Japanese love their natural hot springs and have many hydrotherapy facilities and hot springs resort destinations all over the country. From natural swimming holes to high-altitude sulfur baths to traditional wooden ryokan, there are dozens of ways to soak, but Beppu is perhaps the most famous. In addition to hot springs, it has giant mud-baths and sand baths too.