The first time I walked into a public onsen in Japan, I did almost everything wrong.
I did not rinse properly before entering. I had my small towel with me but did not know what to do with it. I made eye contact with another bather in a way that I later understood was strange. I stayed too long in the hottest pool because I thought leaving quickly would be impolite.
Nobody said anything to me. That is very Japanese. But the looks I received were unmistakable, even through the steam.
I went back the next day and the day after that. I watched carefully. I started asking Ryan questions too. He lived in Japan for around five years and has picked up the customs the way you do when something becomes part of your daily routine rather than a tourist experience. He knows the rules. He does not always know how to explain them, because some of it is just absorbed habit at this point. But between his years of practice and my stubborn determination to get it right, we have pieced together a fairly complete picture. This is what we know.
This is the single most important rule of Japanese bathing and the one most visitors overlook.
Before entering any communal bath, you must wash your entire body at the shower stations along the wall. This is not a quick rinse. It is a proper wash with soap and shampoo, the same thorough job you would do at home. The communal water must stay clean for everyone who follows you. Japanese bathing culture treats this with complete seriousness.
The shower stations usually have a small wooden or plastic stool and a bucket. Sit on the stool. Use the handheld shower attachment. Work from your hair down. Some facilities provide soap and shampoo. Others expect you to bring or purchase your own. Check at the reception.
Once you are clean, rinse off all the soap completely. Then you may enter the bath.
You will be given a small towel, or you may bring one. It is not for drying yourself in the bath. It serves a different purpose entirely.
In the bath area, keep your towel off your head or folded neatly beside the pool. Many bathers place it folded on top of their head while soaking. This looks strange the first time but makes practical sense: it keeps the towel dry, it prevents it from touching the water, and it keeps your head cool while your body is in the heat.
Never put your towel in the water. This is one of the clearest signs that someone does not know the customs, and it genuinely does contaminate the bath for others.
When you finish soaking, use the towel to dry yourself before returning to the changing area. Dripping water across the floor between the bath and the changing room is considered careless.
Most onsen facilities have multiple pools at different temperatures. There will usually be a main bath, a hot bath, and sometimes a cool or cold plunge pool. The rotenburo, or outdoor bath, is typically a third option.
Do not dive straight into the hottest pool. This is hard on your cardiovascular system and also startling for the other bathers. Start with a cooler pool and work your way up gradually. Give your body time to adjust.
Japanese baths can be genuinely hot. Temperatures between 40 and 44 degrees Celsius are common. Some famous springs like Kusatsu are hotter. If the water feels too intense, move to a cooler pool rather than trying to endure it. There is no award for suffering in silence.
The recommended soak length is typically 15 to 20 minutes per session, with a break between sessions if you plan to bathe multiple times. Many onsen regulars follow this pattern: soak, rest, cool down, soak again. The rest period is part of the experience, not an interruption of it.
This sounds like an odd category but it is important.
Do not swim. The bath is not a swimming pool.
Do not splash. The water is shared. Keep your movements quiet and considered.
Submerge only up to your shoulders. Full submersion of the head is not the custom in shared pools.
Do not wash your hair or body in the communal bath. That happens before you enter, at the shower stations.
Try not to stare at other bathers. This sounds obvious but becomes less so when you are in an unfamiliar environment and trying to figure out what everyone else is doing. Watch when necessary, look away when not.
Silence is generally observed, especially in smaller or more traditional facilities. Quiet conversation is acceptable at most places. Loud conversation is not. Phones are almost always prohibited in the bathing area entirely.
Many onsen facilities include a sauna room alongside the baths. The hygiene rules here are taken just as seriously, and there is one specific custom worth knowing in advance.
Sauna rooms in Japan often have a stack of thin sitting boards near the entrance, usually made from foam or a lightweight material. These are for placing under you while you sit on the sauna bench. The bench is shared by everyone, and the board prevents direct contact between your body and the wood. Using one is expected, not optional.
When you leave the sauna, you wash the board. There is typically a bidet or a small spray attachment near the sauna exit for exactly this purpose. You rinse the board, let it drain, and return it to the clean stack. This is not something anyone will necessarily explain to you in advance. It is simply what you do. Ryan figured this out by watching others and explained it to me when I asked why everyone was rinsing a small foam square before leaving the room.
The underlying principle is the same as everything else in Japanese communal bathing: you leave the space exactly as clean as you found it, or cleaner. The next person should encounter no trace of your visit.
Almost all onsen in Japan are gender-separated. Men and women bathe on different sides of a dividing wall. Some facilities rotate which side is for men and which for women on alternate days, or at different times of the day. Check the signs carefully. The characters to know are for men and for women.
A small number of onsen offer konyoku, meaning mixed bathing. These are the traditional form, and they exist mainly at older, more remote facilities. Tsuru-no-yu in Akita is the most famous example. The water is typically opaque enough to preserve modesty, which is by design rather than coincidence. The etiquette at mixed-bathing facilities is notably conservative. Keep to yourself. The point is the water.
Japan has a long history of prohibiting tattoos in public baths. The rule originated in policies designed to exclude organised crime members, who often have distinctive tattoos. Many facilities maintain this policy today, regardless of the reason for a person's tattoo.
If you have visible tattoos, call ahead or check the facility's policy before visiting. More facilities are becoming flexible, particularly smaller family-run onsen and inns that cater to international visitors. Larger resort bathhouses tend to maintain stricter policies. The approach that causes the least awkwardness for everyone is simply to ask before you arrive.
Private baths, known as kashikiri, are an excellent option if you have tattoos and want to avoid the shared pool entirely. Many ryokan offer these as rentable rooms, typically booked by the hour. The experience is different but worthwhile.
Tie long hair up before entering the bath. Hair should not trail in the water.
Remove all jewellery. Beyond the etiquette aspect, metal can tarnish or react in mineral-rich water.
If you feel dizzy or overheated, get out. The heat combined with low blood pressure or dehydration can cause lightheadedness quickly. Drink water before and after bathing.
Do not go in if you are unwell, have open wounds, or are heavily intoxicated. These are printed rules at most facilities, not suggestions.
The changing room has its own rhythm. Put your shoes in the shoe locker before the main entrance. Your clothes and valuables go in a basket or locker inside the changing room. Many facilities use a key system tied to a wristband. Keep it on your wrist throughout.
Take your time after bathing. The rest period is part of the experience. Many ryokan have a resting area near the bath where you can lie down, drink cold water or green tea, and let your body temperature normalise before getting dressed.
Getting dressed immediately after stepping out of a hot bath is uncomfortable and unnecessary. Sit. Cool down. The day is not in a hurry.
I think about that first visit often. I was doing my best with no information and a lot of goodwill. Nobody at a Japanese onsen will humiliate you for making mistakes. The culture is too considerate for that. But arriving with some understanding of the customs changes the experience entirely. You stop monitoring yourself and start actually being there. In the water. In the heat. Somewhere very far from your ordinary life.
That is the whole point.
Ria Flores is an interior designer, Chief Design Officer, and frequent Japan traveller who has soaked in hot springs across Hokkaido, Tohoku, Kyushu, and Kansai. She writes about onsen culture from a traveller's perspective — practical, personal, and grounded in first-hand experience. She is the wife of SpringsAtlas founder Ryan Flores.
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