Pamukkale, Turkey

The 35 °C warm Cleopatra pool above the sinter terraces is said to have been visited by the Egyptian queen - nowadays tourists from all over the world visit for a mineral bath. © Stocksy

There probably is hardly anyone who has never heard of Pamukkale, the Turkish "cotton castle": For over thousands of years, spring water has formed natural sinter terraces through the finest mineral deposits, which shine in alabaster colors. They are Turkey's most visited tourist destination - and enjoyed great popularity even 2,000 years ago, as the ancient Greek spa town of Hierapolis, which towers over the spring basins of Pamukkale, impressively attests. People from near and far came here looking for relief from their rheumatic ailments, for example - today, people are mainly on the lookout for the perfect photo.

Grutas Tolantongo, Mexico

The Pozas Termales (small thermal pools covered in limestone) carved into the hillside offer a unique bathing experience with views over the canyon. © Shutterstock

Although they are just four hours from Mexico City, the thermal springs of Tolantongo National Park in the Mezquital Valley in Hidalgo are still a real insider tip among travelers. The volcanic activity of the region heats up the rivers, pools and waterfalls of the canyon properly: Up to 36 °C hot water washes around the bathers; due to its high mineral content, it shines in an almost unreal turquoise blue and is said to treat skin diseases. In between are impressive grottoes, the "grutas," with their warm water pools and tunnels that become natural steam saunas due to the evaporating hot water.

Castle Hot Spring Resort, USA

The water of the three thermal pools originates from a spring depth of up to 3.000 meters and promises a particularly pure, clear and odorless bathing experience. © provided

Even Theodore Roosevelt and John F. Kennedy crossed the Sonora Desert to spend relaxing hours in this oasis: "Castle Hot Springs Resort" is not only one of the most popular wellness resorts in Arizona, but also the oldest. Even before Frank M. Murphy founded the hotel in 1894, the indigenous Yavapai and Apache made pilgrimages to the site to harness the powers of the waters (which range from 29 to 41 degrees Celsius and are said to have mood-lifting and pain-relieving properties) for ritual purposes. Today, guests from all over the world float in the spring water, which flows over rock cascades into three pools, each of different temperature.

Travertine Hot Springs, USA

The travertine terraces in California offer a majestic backdrop: Behind the basins towers the High Sierra, California's mountainous backbone. © Mauritius Images

Not only hot baths, but also impressive views of the Sierra Nevada await visitors of the Travertine Hot Springs in California. Over the past millennia, the thermal water has formed travertine terraces of white limestone interspersed with colorful mineral streaks. Numerous natural and artificial pools of various sizes and temperatures, at the bottom of which there is sulfurous healing mud (for soft skin), invite you to take a desert bath at the Travertine Hot Springs - and have been doing so for 10,000 years, as archaeological finds prove: even the Paleo-Indians enjoyed spending their days at the thermal spring. Today, tourists from all over the world do the same.

Hierve el Agua, Mexico

The fossilized waterfalls Hierve el Agu , the smaller of which has natural pools, tower over the stunning Mexican mountains of Oaxaca. © GettyImages

The water also bubbles up in the mountains of Oaxaca, between flowering cacti and mighty holm oaks - Hierve el Agua is one of those places you have to see once in your life. Over thousands of years, mineral deposits of carbonated spring water have formed two natural cascades of white travertine rock that drop an impressive twelve to 30 meters. These formations are also called "Cascadas pétreas", meaning "petrified waterfalls". Below the smaller "Cascada chica," bathers immerse into thermal pools at a pleasant 22 to 27 °C, while all around them the mountains present themselves in their full splendor.

Cascate del Mulino, Italy

Due to its high sulfur content, the thermal water has a healing effect on the respiratory tract, alleviates skin problems and ensures good blood circulation. © Eva Phan/eva-darling.com

Hidden among the hills of southern Tuscany, nature has created a small spectacle in the village of Saturnia: Thermal water at 37.5 °C, which helps with respiratory diseases and high blood pressure, emerges from the depths of the earth here and flows down the extinct volcano Monte Amiata like a waterfall. Right next to a mill, amazing limestone pools have formed, varying in size. The Etruscans immersed themselves in these bright blue natural pools 3,000 years ago, followed by the Romans, who considered the Cascate a refuge of the god Saturn and founded a public spa near it.

Vals 7132 Hotel, Switzerland 

At the "7132 Hotel" in Vals, you can combine the thermal water bath with soothing signature treatments - from massages to scrubs - at the spa. © provided

Graubünden's only mineralized spring is in the tranquil village of Vals, where it provides for, among other things, the spa of the five-star superior hotel "7132 Vals". However, before it ends up in the architecturally outstanding bathing halls (designed by Swiss star architect Peter Zumthor), the 30 °C warm water has been traveling in the depths of the Alps for up to 80 years. On its journey to the surface, it enriches itself with numerous minerals. The water's inherent healing properties (it is said to work wonders for rheumatic and nervous disorders, for example) were already known in the 17th century; for more than 100 years, the spring has been the location of the bathing facility.

Tabacòn Resort, Costa Rica

Spring water is also ubiquitous at the resort itself - in the main pool, for example, which also features a chic swim-up bar with a palapa roof. © Adobe Stock

Costa Rica's youngest and most active volcano towers almost threateningly over Tabacón and the surrounding jungle - but if you let yourself drift in the hot geothermal springs at the foot of the Arenal, you won't lose your cool anytime soon. On the contrary: in the thermal river heated by the volcano, 18 pools and idyllic waterfalls, which are part of the award-winning Tabacón Resort & Spa, invite you to bathe in the hot water and gently relax tense muscles. Since the five-star resort was founded in the 1990s, you can also look forward to exquisite spa treatments such as volcanic mud wraps and coffee scrubs.

The Retreat at Blue Lagoon, Iceland

Guests of the "Retreat" have exclusive access to a private part of the lagoon, bordered by centuries-old lava rocks. © Giorgio Possenti/giorgiopossenti.com

Even in the far north of Europe, deep under rock and ice, water is swirling: Iceland is known for strong geothermal activity, for volcanoes, but also for geysers and hot springs - just like at the famous Blue Lagoon. The thermal outdoor pool just outside Reykjavik, created as a byproduct of a geothermal power plant, scores with warm seawater that rises from a depth of about 2,000 meters and comes to surface at a comfortable 38 °C. The high content of silicon dioxide, algae, and silica (which is responsible for the iconic turquoise of the 5,000-square-meter lagoon) has been studied to have a healing as well as rejuvenating effect on the skin.