Onsen – Japan's Natural Hot Springs

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The onsen (温泉) are natural volcanic hot springs that are appreciated and help to relax, also bringing numerous health benefits. In this article, we will talk in detail about these Japanese spas.

For those who don't know, Japan is a volcanic country full of natural and artificial hot springs, it is not an exaggeration to say that onsens are the passion of Japan. There are thousands of varieties of hot springs in Japan.

Visiting the bathrooms and hot springs is part of Japanese culture, since childhood, families have frequented this place and enjoy the countless benefits that hot springs offer.

In the hot springs people need to bathe naked, which is very uncomfortable for Westerners, but it is something extremely normal among Japanese people. The bathrooms are separated by sex, but in the past the hot springs had a mixed bath.

Onsen - Japan's Natural Hot Springs

Some curiosities about onsen

Research claims that there are more than 30,000 natural hot springs across Japan. More than 3,000 resorts and thousands more spread across mountains and cities. If we count the unnatural the numbers go over 100,000.

Visitors usually wear a small towel-apron. Some places allow the Japanese to enter the water with a towel. Otherwise, the Japanese usually place the folded towel on the head or in the corner of the pool.

Visitors should wash their bodies and dry themselves before entering hot water. The indoor baths provide small benches for visitors to sit and take a shower.

Onsen - Japan's Natural Hot Springs

Many traditional hot springs in Rural Japan have rules that prohibit the use of bath robes, arguing that it makes cleaning more difficult. While others allow access to the site wearing a yukata, but rarely will an onsen allow anyone to enter clothes in the waters.

The purity of water is very important in onsen, so people need to bathe naked and take a shower before entering the thermal pools. You can't even touch the water with the towel.

Young children can accompany a parent during the bath, regardless of gender. The girls who accompany the father in the men's bath wear clothes and bikinis. In some hot springs in the mountains, you can even come across mischievous monkeys.

Onsen - Japan's Natural Hot Springs

The hot springs are generally considered a refuge from the stressful life that the Japanese lead, the springs have a calm and relaxing atmosphere. Many hot springs have an image of Mount Fuji on the walls, which according to tradition, encourages calm and meditation.

The waters are generally rich in minerals. Mineral water content and PH levels vary widely from one onsen to another. The waters can be rich in iron, sodium chloride, sulfur, carbon or radium.

One of the goals of Japanese hot springs is to cure a disease. There is a type of source for each disease. Couples who are trying to get pregnant go to an Onsen. Elderly people go to spas to improve circulation or calm joint pain.

Onsen - Japan's Natural Hot Springs

The waters of the springs are considered hot in the west from 21 degrees, whereas the hot springs in Japan are only classified from 25 degrees. Water must have at least 1 of the 19 types of minerals.

Hot springs are one of the ways to connect with nature and people. It's common to talk to strangers. Many Japanese firmly believe that hot springs can make friends, have fun with coworkers, couples and family.

Remembering that each onsen has its rules, there are tags and ways to bathe in thermal water.

Rotenburo - outdoor onsen

Rotenburo they are onsen outdoors and are considered more desirable than the indoor spa. Part of an onsen's experience is connecting to nature, something you only find when visiting these remote spas in the mountains.

Onsen - Japan's Natural Hot Springs
Onsen Hot Spring

Many rotenburo have an excellent view of the mountain, forest or sea. In regions of northern Japan the Rotenburo is surrounded by snow. Some rotenburo they are pools that arose naturally, without human interference.

Many Rotenburu-style onsen are built by resorts and hotels. The best rotenburo they are constructed of natural materials, they are generally landscaped and maintain privacy for visitors.

Some onsen in cities usually reserve a more natural location similar to rotenburo. Even in a multi-storey building it is possible to find an onsen where a part of it is exposed to the open air, without any cover.

Onsen - Japan's Natural Hot Springs
Monkey in the Onsen

Private Onsens - Some Hotels and Resorts, offer a private onsen in the rooms, are small bathtubs with artificial or natural thermal waters. Other onsen also offer private rooms for couples and friends.

Konyoku onsen - Mixed Bath

Konyoku are mixed sex onsen, which are found in the countryside. In some cities like Tokyo, Konyoku are illegal. I have already visited a mixed onsen on the mountain, where the pools were closed in small rooms and yukata were used to get from place to place, making it almost impossible to see a naked woman as some wish.

The Konyoku were quite popular in the Edo period, with Western influence this became unusual. Although some places allow mixed bathing, a large part of the public in these baths is over 60 years old, probably young people have created shame and do not frequent these mixed places.

We’ve already written an article talking in detail about mixed baths and where to find them in Japan. Mixed baths are called konyokuburo (混浴風呂) and are more organized than you think. 

Onsen - Japan's Natural Hot Springs

Sento - Thermal baths in the city

Sento are similar to onsen, except that their water is heated artificially. Sento often uses normal water that does not have the mineral properties of the onsen. Sento are often found in urban areas.

In the past, many families did not have a bathtub at home, so it is common for them to go to a small seat. Even though most of them today have a hot tub at home, the sento are still very successful in Japan.

Onsen - Japan's Natural Hot Springs

Types of water and bath in the onsen

Each onsen has its kind of natural water each with its own benefit. We’ve already written an article about it, but let’s list a little bit of the types of water that we find in Japanese hot springs:

Chloride - Enka butsusen (塩化物泉) - With magnesium, calcium and sodium, this type of thermal water cures cuts and burns due to the high salt content. It promotes skin hydration and helps you maintain body heat, perfect in winter.

Sulfate 額隠 – 神秘的日本白布 Ryusan sen - This type of onsen is good for healing cuts and bruises, fighting chronic constipation and arteriosclerosis. Water also provides moisture to the skin. Sodium sulfate helps against high blood pressure, while calcium sulfate helps against rheumatism.

Alkaline or sodium bicarbonate saline 額隠 – 神秘的日本白布 Tansan suiso ensen - These thermal waters look thick and you feel a silky smoothness on your skin after taking a shower. Alkaline water helps to melt sebum, exfoliates the skin and removes spots. This onsen is a favorite among women who want perfect skin. We recommend the hinokamiso, ureshino, kitsuregawa and saksuikan onsen.

All types of saline water help heal cuts, burns and chronic skin disorders. Sources of chloride and sodium bicarbonate are not recommended for people with kidney problems, hypertension, thyroiditis or swelling.

Different types of onsen hot springs and their benefits

Sulfur - Iousen - (硫黄泉) - Sulfur onsen is found mainly near volcanic waters. Its smell is distinct and its color is milky, it is believed that this water can help treat skin disorders and arthritis. Sulfur is rich in vitamin B1, B5, H and promotes metabolism and communication between nerve cells. Perfect for relieving rashes, itching, eczema, dandruff and warts as well as protecting the body from toxins.

Iron - Gantetsu sen - In these onsen the water is rust colored, can be found in ikaho onsen. It helps in the body’s ability to retain heat, restores body iron levels, perfect for anemias, rheumatism and menstrual disorders. It also increases the quality of your blood, prevents stress, fatigue and improves skin tone. There are 2 types of water with iron, carbonated and melanterite. Do not be alarmed by the brown color of the water, this is a concentration of iron and not dirt.

Hydrogen / Carbonate - Tansansen (炭酸泉) - The carbonated waters create several fine bubbles that stick to the skin. This carbonated water is said to improve blood circulation by up to 5 times that of normal water. Blisters also help remove waste from the body and detoxify. There is a beauty trend in Japan, where people cleanse their skin with carbonated water.

Different types of onsen hot springs and their benefits

Special baths in the Japanese spa

Aluminum 額隠 – 神秘的日本白布 Ganaruminiumusen - This onsen has acidic properties, which provide sterilization effects. It has a bitter taste, said to be useful in the treatment of various skin diseases such as athlete’s foot, rashes and dermatitis.

Acido - Sansei sen - These thermal waters provide an antibacterial effect, but it is not recommended for people with sensitive skin, the acid can irritate it. Recommended for those who have sagging skin, want to treat rheumatism or make the skin more beautiful, as the acid eliminates dead skin cells.

Radiation 額隠 – 神秘的日本白布 Hoshano sen - Yes, they are rare but there are spas with slightly radioactive waters that are not harmful to health. This mildly radioactive water is said to be good for arthritis, and some even claim to kill some tumors. In addition to improving metabolism, boosting immunity and healing the body’s energy. Water when inhaled, improves the body’s antioxidant function, helps in anti-aging and prevents diseases. Just don’t give super powers…

Carbon dioxide - Niisanka-tanso ensen - With about 100 milligrams of carbonic acid per kilogram, the water has a fine foam on the surface. They are rare, but they help against cuts, burns, arteriosclerosis and hypertension by expanding blood vessels.

Cold shower - Some onsen have icy pools that can help stimulate nerve endings, treat depression, release testosterone, stimulate the lymphatic system, fight infections, boost immunity, etc.

Different types of onsen hot springs and their benefits

Where to find an Onsen?

There are more than 100,000 hot springs in Japan. They can be found in their own places or in hotels, ryokan and pensions. There are also public and private Onsen that are not part of a hotel or residence.

Onsen ranges from a natural location in the middle of the forest to modern onsen resorts with dozens (or hundreds) of baths. Onsen can be found even in big cities like Tokyo or small cities that we don’t even find right on the map.

However, the vast majority of the hot springs are in the mountains and in the countryside. Japan has dozens of Onsen spas like Atami and Hakone (near Tokyo). Each city can have dozens of Onsen baths.

Onsen - Japan's Natural Hot Springs

To find an onsen we recommend using the Google Maps and search for onsen [温泉], sento [銭湯], hot spring or the other terms we mentioned in the article.

And do you dare to go on an Onsen? Or are you ashamed? Leave your comment, and share with friends. Finally, I’ll leave a video, we recommend reading our article on different types of onsen hot springs.

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