The Onsen Experience: Healing and Rejuvenation in Japan’s Hot Springs

Imagine sinking into water warmed by the Earth itself, steam curling gently into the crisp mountain air, carrying faint scents of sulfur or hinoki cypress. Feel tension release from tired muscles, the smooth caress of mineral-rich liquid against skin, and a profound sense of peace settling over your mind and body. This is the essence of the Japanese Onsen, the nation’s beloved hot springs.

There are approximately 27,000 natural hot springs (Onsen) dotted across the country. These are not just a spa experience but there is science and spirituality behind this uniquely Japanese culture. The quiet and often scenic surroundings of an onsen further contributes to a sense of calm and tranquility. You are required to adhere to strict etiquettes when visiting one of the mineral-rich hot springs (yes, you will be in the buff like everyone else – be prepared). At the same time, visiting an Onsen in Japan can be a memorable way to experience the natural beauty and culture of it’s different regions. 

The healing waters: Science behind Japanese hot springs 

Japan’s Onsen is a fascinating blend of time-honoured tradition and emerging scientific understanding. For centuries, these geothermal springs have been revered not only for relaxation but also for their profound healing capabilities, a belief now increasingly supported by modern research.

Scientific research, including studies from Kyushu University’s Onsen Therapy Research Institute, confirm the health benefits of Onsen bathing backed by physiological and microbiological evidence, such as improved circulation and metabolism, muscle relaxation and pain relief, stress reduction and improved sleep, promotes skin health, gut health modulation and potential benefits for chronic conditions like rheumatoid arthritis, bronchial asthma, diabetes mellitus, and improved cardiovascular health. 

Toji (湯治) refers to the practice of staying at an Onsen for an extended period, often weeks, bathing multiple times daily specifically for therapeutic purposes to treat ailments. Dating back over a millennium, Toji sites were often pilgrimage destinations, sometimes discovered by monks or associated with emperors seeking cures. This practice of Toji highlights the deep-seated cultural belief in the water’s healing power.

Japanese onsen: health-enhancing minerals

The therapeutic potency of Japan Onsen is intrinsically linked to the unique cocktail of minerals dissolved in the water. Presence of these minerals is a direct result of the complex geology beneath Japan’s volcanic terrain.The Japanese Hot Springs Act (Onsen Hō) defines Onsen based on temperature (at least 25°C at the source) or the presence of specific minerals above certain concentrations, even if the temperature is below the threshold. 

Different types of Onsen offer distinct benefits. Understanding this will help you choose an experience tailored to your needs:

Sulphur Springs (Iosen 硫黄泉): 

• Characteristics: Milky appearance. “Rotten Egg” smell
• Benefits: Skin conditions (eczema, psoriasis, acne), high blood pressure, joint pain, arteriosclerosis, gut bacteria modulation (Alistipes, Ruminococcus)
• Onsen Locations: Noboribetsu, Kusatsu, Myoban (Beppu)

Bicarbonate Springs (Tansan Suiso Ensen 炭酸水素塩泉):

• Characteristics: Often clear, feels smooth (“beautifying baths”)
• Benefits: Skin softening/exfoliation, pore cleansing, gut health (B. bifidum increase: glucose tolerance, constipation relief, gut immunity)
• Onsen Locations: Ureshino, Hijiori, Noboribetsu

Chloride Springs (Enkabutsusen 塩化物泉): 

• Characteristics: Salty taste, excellent heat retention (“heat baths”)
• Benefits: Improved circulation, wound healing, burns, muscle/joint pain relief, keeps body warm
• Onsen Locations: Atami, Shirahama, Noboribetsu

Iron Springs (Gantetsusen 含鉄泉): 

• Characteristics: Clear or reddish-brown (“gold/silver springs”)
• Benefits: Anemia, fatigue recovery, wound healing (collagen), skin tone/oxygenation
• Onsen Locations: Arima, Shibukawa Ikaho 

Carbonated Springs (Tansan Sen 炭酸泉): 

• Characteristics: Bubbly sensation on skin
• Benefits: Improved blood circulation (CO2 absorption), cardiovascular health (“heart baths”), potential skin rejuvenation (collagen)
• Onsen Locations: Nagayu (Oita), Taketa City (Oita) 

Radium Springs (Hoshano Sen 放射能泉):

• Characteristics: Contains traces of natural radon
• Benefits: Pain relief (gout, neuralgia, rheumatism), improved metabolism
• Onsen Locations: Misasa, Naruko Onsen Village 

Acidic Springs (Sansei Sen 酸性泉):

• Characteristics: Low pH due to presence of sulphuric or hydrochloric acid. Can cause skin & eye irritation to some. 
• Benefits: Strong bactericidal effect, good for athlete’s foot, certain skin diseases
• Onsen Locations: Kusatsu, Tamagawa, Sukayu

Simple Springs (Tanjun Sen 単純泉):

• Characteristics: Low mineral content, mild
• Benefits: Gentle, good for beginners/sensitive skin, gut bacteria modulation (Oscillibacter, Parabacteroides)
• Onsen Locations: Widely available

Humic Acid (Black Onsen / Kuroyu 黒湯):

• Characteristics: Dark brown/black color
• Benefits: Skin smoothing, neuralgia relief, fatigue recovery
• Onsen Locations: Kamata (Tokyo), Aomori 

Beyond the main categories, other ions present are Lithium, Strontium, Manganese, Iodine

• Benefits: Anti-inflammatory, acne relief (Li); Skin barrier, anti-itch (Sr); Antioxidant, collagen (Mn); Antiseptic, hydration (I)
• Onsen Locations: Vary 

As you can see, the Japanese Onsen are not your regular spa treatment with artificial products. Created by mother nature herself, the onsen waters are distinct and varied. Choose your Onsen experience based on specific health benefits or try the simple Onsen to relax, rejuvenate and experience Japan. 

Onsen Sacred Ritual: Water, Purity and Spirit

The Japanese Onsen culture is deeply connected to Shinto spirituality, embodying the faith’s emphasis on harmony with nature and water purification. Soaking in Onsen is seen as a ritualistic cleansing of the spirit, transcending physical hygiene and fostering a balanced life in harmony with nature. The natural setting connects bathers with the divine forces believed to reside in nature. The meticulous etiquette, particularly the emphasis on washing thoroughly before entering the pristine communal water, mirrors the preparatory steps of Shinto purification rituals. It reflects a profound respect for the shared natural resource and for the other bathers. The quiet, contemplative atmosphere encouraged within the bathhouse facilitates mindfulness and allows for a mental and spiritual release.

Historically, Onsen were considered sacred sites, with temples and shrines often constructed near them. Onsenji Temple in Kinosaki, for instance, is traditionally visited to offer prayers before bathing, honouring the priest credited with discovering the springs. 

Best time to visit Onsen in Japan

The Onsen experience is inextricably linked to the appreciation of nature’s transient beauty. Bathing facilities, especially outdoor rotenburo, are often designed to harmonise with and showcase the surrounding landscape, making the changing seasons an integral part of the soak.

• Autumn (September – November): Autumn is one of the most beautiful season for Onsen, thanks to the spectacular fall foliage (koyo or momiji). Soaking in a rotenburo while surrounded by a tapestry of fiery reds, brilliant oranges, and golden yellows is an unforgettable visual feast. Mountainous regions like Hakone, Kusatsu, and Nikko are renowned for their autumn colors. This season is also perfect for indulging in the rich flavors of autumn harvest ingredients featured in kaiseki meals at ryokan. The crisp air and tranquil atmosphere offer a peaceful retreat before the onset of winter.
• Winter (December – February): Perhaps the most iconic seasonal Onsen experience is Yukimi-buro (雪見風呂) – snow-viewing bathing. Soaking in the steaming heat of an outdoor bath while snowflakes drift down onto a serene white landscape creates a magical, almost surreal contrast. Regions famous for reliable snowfall, such as Kusatsu, Noboribetsu, Ginzan, and mountain resorts like Shibu Onsen, offer prime opportunities for this.
  • December often brings festive illuminations and special holiday meals to Onsen towns.
• Spring (March – May): Early spring is marked by the arrival of cherry blossoms (sakura). Many Onsen, particularly those in regions like Hakone and Arima, are situated near cherry trees, allowing bathers to gaze upon the delicate pink blooms while soaking – a quintessential Japanese experience combining two beloved traditions.
• Summer (June – August): While Japan’s summers can be hot and humid, Onsen still offer refreshment, especially outdoor baths surrounded by lush, deep green foliage. The sounds of cicadas, rustling leaves, and nearby streams can enhance the natural immersion. Highland Onsen resorts offer cooler temperatures. Summer is also a time for local festivals (matsuri) in many towns, allowing visitors to combine relaxing soaks with vibrant cultural experiences featuring music, dance, and fireworks. It’s an ideal season to pair Onsen visits with hiking or exploring nearby nature trails.
  • Schedule your onsen visit in the early evening when temperatures start cooling slightly.
• Golden Week, Obon and New Year: These holidays (late April to early May, mid-August, and late December to early January, respectively) are very busy and expensive, making them unsuitable for budget travellers. 

Onsen etiquette in Japan: The art of the soak

Participating in the Onsen ritual is a rewarding cultural experience, but understanding and respecting the established etiquette is crucial for ensuring a comfortable and harmonious environment for everyone.

Step-by-step Onsen ritual: A first-timer’s guide 

• Arrival & Changing: 

Shoes: Remove your outdoor shoes at the designated area (genkan). Put on indoor slippers. 

Changing rooms: Proceed to the correct changing room, identified by gender signs (女 onna for women, often with a red noren curtain; 男 otoko for men, often blue or purple).

Nudity: Remove all clothes (including swimwear or underwear) and store in locker or basket. You get to bring a large towel and a small hand towel. Store the large towel in the locker and take only the small towel with you. Head to the bathing area.

For first timer’s, going buff can be daunting. Try to let go of the awkwardness and you will find the experience liberating. After a few times, the mortification naturally washes away allowing you to truly enjoy this classic Japanese experience. 

If you’re not comfortable with public bathing, many onsen hotels offer private baths or onsen rooms. 

Tattoos: Many traditional Onsen and ryokan maintain strict “no tattoo” policy, while others may allow small, inconspicuous tattoos, tattoos that can be covered, or make exceptions for foreign visitors. Always check specific Onsen policy before visiting. 

• Washing (Kakeyu & Cleansing): This is the most critical step.

Washing Stations: Locate the washing stations in the bathing area. Before washing fully, it’s customary to perform kakeyu: use a bucket to scoop some water from the bath basin (or use the washing station faucet) and pour it over your lower body (feet, legs, waist). This helps acclimatise your body to the water temperature and is a gesture of respect. Then, sit on one of the stools (it’s polite to rinse the stool before and after use) and wash your entire body and hair thoroughly. Some Onsens may provide Soap and shampoo so check beforehand (or carry yours).

Respect: Be mindful of neighbours. Avoid splashing them while washing. 

• Entering the Bath: Enter the water slowly and gently. Avoid jumping or splashing. If the water feels very hot (Japanese Onsen can be 40-44°C or higher), lower yourself in gradually, perhaps starting waist-deep to acclimatise.

Don’ts 

1. You can take your small towel with you but do not let it touch the bath water. Fold and keep on your head, like the experts do (this can also help prevent overheating). 
2. Do not let your hair touch the water. 
3. Avoid loud conversations, swimming, playing, or running. The Onsen is a place of quiet contemplation. 
4. No Photos: Leave your phone & camera outside the bathing area. 
5. Do not eat or consume alcohol before or during the bath.

Do’s 

1. Listen to your body: if you feel dizzy (due to the heat), exit the bath and sit down, cool your body, then re-enter. 
2. Drink water: stay hydrated before, during, and after your Onsen soak. 
3. Enjoy the Experience: Take time to relax and enjoy the hot springs. It’s a great opportunity to unwind and experience a piece of Japanese culture. 
4. Exiting: Before returning to the changing room, use your small, damp washcloth to wipe down your body, removing as much excess water as possible.

Conclusion 

Whether you seek the therapeutic benefits, the serene connection with nature across changing seasons, or a mindful retreat reflecting centuries-old rituals, Onsen bathing offers an unparalleled way to rejuvenate both body and spirit. Embracing the etiquette, understanding the cultural significance, and immersing oneself in the tranquil waters allows for an authentic encounter with Japan’s cherished customs. 

The Japanese Onsen experience is far more than a travel check-list—it is an invitation to pause, reflect, and harmonise with the world around you.