Onsens: A Guide to the Hot-Springs of Japan

Man in onsen with snow monkey
Stefan Powell from Toronto, Canada, Onsen with monkey Jigokudani, CC BY 2.0

Japan is made up of volcanic islands – and that is both a blessing and a curse. One of the benefits is the abundance of onsens scattered across the country. They are great for socializing, relaxing and are places for healing since these natural hot springs are known for their health benefits. In this guide to Japanese onsens, we will be looking at what they are, their health benefits, the types, and the proper onsen etiquette one should adhere to when visiting them.

Topics Covered

  • What is an onsen?
  • Onsen etiquette
  • Types of onsens & health benefits
  • Potential health risks
DescriptionBuy
Onsen bath mineralsJapanese Onsen Bath Minerals – Turn your bath into an onsen with pagoda tree flower enzymes and bamboo extract, which will help hydrate your skin and improve your quality of sleep.
Onsen grade towelsOnsen Grade Towels – A set of 6 light blue highly absorbent cotton towels made in Japan.
Wood onsen setHinoki Wood Onsen Set – This 3-piece set includes a hot water tub, bath chair, and a soap stand. The products are made from hinoki wood in Japan.

The guys from Only In Japan visit 13 different onsen towns in the Fukushima Prefecture. The video is owned and created by Only In Japan.


What is an onsen?

An onsen is a natural hot spring that works similarly to a Japanese bathhouse (sento). A sento uses plain heated tap water while onsen water comes naturally from the ground and is geothermally heated by mother nature. These natural hot springs are much more popular and preferred to Sento’s because the water is naturally enriched with minerals and therefore carries a variety of health benefits.


Onsen etiquette

There are specific rules one should adhere to when visiting a natural hot spring in Japan. These rules are important because many other people use these facilities too.

Tattoo policy

Many facilities do not allow entry to individuals who have tattoos, and the reason is to keep yakuza members out. Even though the chances of you being mistaken for a yakuza member are slim, the rules still apply to everyone. Luckily, most places have become a lot less strict with this over the last few years as a result of the influx of foreign visitors to Japan. If you have a tattoo, it’s advised to phone them beforehand and ask about their tattoo policy. Most will allow entry as long as the tattoo is small enough to be appropriately covered up with a waterproof bandage.

Rinse off before entering the onsen

Everyone has to wash and rinse off before entering the pool since it’s a communal area. There are washing facilities on the premises where you are provided with a bar of soap and a towel but bringing your own is perfectly fine too.

Hair policy

Those who have long hair must tie their hair together with a hairband before entering the water. It’s not easy to enjoy an onsen while hair strands are floating around.

Full nudity is a must

The vast majority of places have a strict rule that one must enter the pool completely nude. You will, of course, have a white towel you can use to cover up as you walk around outside. You are expected to keep your towel with you even when inside the onsen, but it cannot get wet, which is why you will always see people carrying their towels on their heads.

No photography allowed

Cameras are strictly forbidden around the pool area, but if you need to take pictures of the onsen or surrounding areas/views, it would be best to get permission beforehand.

Noise levels and alcohol consumption

The consumption of alcohol is not allowed. Apart from safety reasons, it’s also to help keep noise levels down not to bother other people.



Types of onsens and their health benefits

The type of minerals found in a hot spring defines the category as they all carry different health benefits. We will also discuss the waning unisex onsen.

Tsurunoyu onsen
Fumiaki Yoshimatsu from Tokyo, Japan, Tsurunoyu Onsen 03, CC BY-SA 2.0

Konyoku onsen (Unisex hot spring)

When you visit onsens in Japan, you will notice they are not unisex. Unisex hot springs, known as a Konyoku Onsen in Japanese, have been banned in the country since the start of the Meiji Era. This doesn’t mean that they no longer exist. It’s just that they don’t exist in the urban areas or large towns but can still be found in the remote regions of the country. Their numbers are in sharp decline, though, and there are estimated to be only a few hundred left.

Io-sen (Sulfur hot spring)

Io sen, or sulfur enriched hot springs, are especially beneficial for your skin. It clears skin; also, the sulfur treats acne, eczema, and a wide variety of rashes. It also improves blood circulation and has a therapeutic effect on people with diabetes. The only downside to this type of spring is that it smells pretty awful as sulfur smells a lot like rotten eggs.

Sansei-sen (Acidic hot spring)

This type of hot spring is not recommended for people with sensitive skin, as the high levels of acid can become a skin irritant. If your skin can handle it, then you can benefit from clearer and tighter skin because the acidic properties strip off dead skin cells.

Tanjun-sen (Simple water hot spring)

Tanjun is the most commonly found hot spring in Japan. They contain low levels of minerals and, therefore, basically carry almost no health benefits. It is, however, great for relaxation and improved blood circulation.

Yufuin onsen
R34SkylineGT-R V-SpecⅡNür, Yufuin Onsen Rotenburo, CC BY 3.0

Gantetsu-sen (Iron hot spring)

Gantetsu onsens can easily be recognized by the red watercolor, which is caused by very high iron content. By merely soaking in this type of onsen, you will raise your red blood count level, which assists your body in retaining heat.

Hoshano-sen (Radioactive hot spring)

As the name implies, it is radioactive because it contains radon. But not to worry, the radon levels are minuscule, and soaking in it can be healthy as it’s beneficial for those suffering from inflammation and joint pain. The entry price for these types of onsens is higher, but that’s because they are very rare.


The potential health risks of onsens

Now it’s time to deal with something a little more unpleasant – the associated health risks of using onsens. And yes, there are quite a few potential dangers involved but not to worry because we will also advise on how to minimize the risks.

Bacterial infections: Most Japanese hot springs are communal areas, while snow monkeys even frequent some. This puts people at risk of disease from bacteria such as naegleria and legionella. Keep in mind that getting an infection from an onsen is extremely rare, and people who run them have recently started adding chlorine to the pools, with some even regularly changing the water. On your part, make sure to wash properly before entering an onsen to help minimize the number of bacteria in the pool. Furthermore, keep your head above water at all times, and you might want to reconsider entering if you have any open cuts or sores.

Dehydration: The average onsen is pretty hot, so you will sweat a lot and most probably not notice it. It can also cause heat overexposure, which results in dizziness and fatigue. Just be sure to drink sufficient amounts of water before entering and limit yourself to 10 – 15 minutes at a time in the onsen.

Blood pressure: Hot springs tend to push up your blood pressure, so if you are already suffering from high blood pressure, you may want to reconsider using an onsen.

Avalanches: Most people don’t realize this, but avalanches pose a very real risk. You would, of course, need to be in an outdoor onsen located next to a mountain in winter for the possibility of something like this to occur. Tragically, such events have taken place numerous times over the last few years.

Slippery surfaces: The surface area around the pools is either rock or wood, and both can be slippery. Practice caution when entering and exiting the onsen. This is also one of the reasons why alcohol and intoxication are prohibited.



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