Hakone Onsen — photo: Quercus acuta · CC BY-SA 4.0 · Wikimedia Commons
Can you wear a swimsuit in an onsen? The rule, where swimsuits are allowed, and what to do if you would rather not be naked
In an ordinary onsen bath, no. You go in with nothing on: no swimsuit, no underwear, no towel wrapped round you. That covers the shared baths at almost every inn and every town bathhouse in Japan. But "onsen" also covers foot baths, sand baths, mixed baths that lend a wrap, private baths and big hot-spring parks, and in some of those you keep something on, or have to. This guide covers why the rule exists, the places where it does not apply, how to read the sign at the door, and what to do if bathing naked with strangers is the one thing stopping you from going.
The rule, and why
A Japanese onsen bath is shared water that a lot of people sit in, often without being changed for hours. The custom is built around keeping it clean: you wash at the shower first, and nothing goes into the water except a clean body. Fabric breaks that. A swimsuit has been in a bag, a pool or a suitcase, and it carries detergent, sunscreen and whatever it touched last. The small towel stays out of the water for the same reason. See how an onsen stay actually works for the towel and the washing.
It is not a question of modesty being frowned on. The baths are separated by gender, marked 男 for men and 女 for women, and people are not looking at you. Carrying the small towel in front of you as you walk to the pool is normal, and many people do it. Putting it into the water is not.
Three questions people ask:
- Underwear? No. The same rule as a swimsuit.
- A towel wrapped round me in the water? Not in an ordinary bath. A few mixed baths allow it; see below.
- A swimsuit just for the walk from the changing room? No. You undress fully in the changing room and leave everything in the basket or locker.
Where a swimsuit is allowed, or required
These are the exceptions. None of them is a loophole in the ordinary bath; they are different kinds of place.
- Hot-spring parks and resort complexes. Some large facilities have pools of hot-spring water where men and women bathe together in swimsuits, closer to a water park than a bathhouse. In Hakone there is one at Kowakudani; see the Hakone guide. In Beppu a few resort complexes have swimwear pools; see the Beppu guide. Many of these places also have ordinary gender-separated baths in the same building, and in those the usual rule applies again. Some rent swimsuits, but bringing your own is simpler.
- Swimsuit zones at big day spas. Some large day spas in and around cities have a separate mixed area where you wear a swimsuit or the clothes the spa gives you, next to naked baths that stay separate. The sign is 水着ゾーン (mizugi zōn). See onsen without staying the night for how day spas work.
- Outdoor river and beach baths. A few free baths in the open, on a riverbank or a beach, have been used in swimsuits because everyone can see them. Their rules change. The riverbed bath in Gero, for example, has been open only as a foot bath in recent years; see the Gero guide. Check the current status before you pack a swimsuit for one.
Where you keep your clothes on
- Foot baths. A 足湯 (ashiyu) is a shallow bath for your feet and lower legs, usually outdoors in the middle of an onsen town and often free. You roll up your trousers and sit on the edge. Bring a small towel to dry your feet. Many onsen towns have one by the station or the main street.
- Sand baths. In Ibusuki you are buried in naturally heated sand wearing a cotton yukata the bath hands you, and men and women do it side by side. Then you wash and bathe in the ordinary way, naked and separated. See the Ibusuki guide.
- Bath wear in some mixed baths. A few mixed baths let women, and sometimes men, wear a bathing wrap, 湯あみ着 (yuamigi), which some sell or lend at the desk. Some allow a towel wrapped round the body instead. This is a rule of that bath only, not a general permission. See mixed bathing in Japan for where mixed baths are left and how their rules work.
Reading the sign
Facilities that allow or require swimwear say so plainly, usually at the entrance or on the price board. These are the words to look for:
- 水着着用 (mizugi chakuyō): swimsuits must be worn. The mixed hot-spring park kind of place.
- 水着可 (mizugi ka): swimsuits allowed.
- 水着禁止 (mizugi kinshi) or 水着での入浴はご遠慮ください: no swimsuits. Many baths do not bother to post this, because it is assumed.
- 湯あみ着 (yuamigi) or 湯浴み着: bath wear, allowed or for rent.
- 貸し水着 (kashi-mizugi): swimsuits for rent.
If none of these words is anywhere in sight, assume the ordinary rule. Asking at the desk is easy: 水着は大丈夫ですか (mizugi wa daijōbu desu ka), "is a swimsuit all right?" Most staff will simply say no and point you to the changing room.
If you would rather not bathe naked with strangers
Plenty of visitors feel this way, and Japanese onsen culture has more room for it than the rule makes it sound. Five ways round it, from least to most effort:
- Book a private bath. A 貸切風呂 (kashikiri-buro) is a bath you reserve for a set time, alone or with the people you came with. Nobody else sees you. Whether a swimsuit is allowed in one is the inn's call; most simply expect you to bathe the usual way, because you are alone. See baths you can have to yourself.
- Book a room with its own bath. A room with an outdoor bath of its own, 客室露天風呂 (kyakushitsu rotenburo), is the surest version of the same thing. It costs more; see what an onsen night actually costs.
- Go at a quiet time. An inn's shared bath late in the evening or early in the morning is often empty or close to it. See when to soak and how long for how inn bath hours work.
- Start with a foot bath or a sand bath. Both give you the hot water and the setting without undressing in front of anyone.
- Go to a swimsuit park. It is a different experience from a quiet inn bath, but it is hot-spring water, and you can go as a mixed group.
If the reason is tattoos rather than modesty, a swimsuit does not solve it: see onsen and tattoos. If it is about a period, see onsen on your period.
What you do take in
The small towel, and that is all. The large towel stays in the changing room. Leave glasses in the basket if you can manage without them; they fog up, and acidic or sulfur water can damage metal frames (see onsen etiquette). Long hair is tied up. Shaving, if you need to, happens at the shower seat, never in the pool. A day-trip kit for town bathhouses, where towels and soap are not always provided, is in onsen without staying the night.
If you did bring a swimsuit for a foot bath or a hot-spring park, keep it away from strong water. Sulfur and acidic water can fade fabric, and the smell stays in it for a while. See the sulfur onsen guide.
Three things not to do
Do not wear a swimsuit into an ordinary bath because nobody stopped you at the door. Somebody will ask you to take it off, and it will be more awkward than undressing in the first place.
Do not wrap a towel round yourself in the water unless the bath's own sign says you may.
Do not skip a whole onsen trip over this. Between private baths, rooms with their own bath, foot baths and quiet hours, there is almost always a way in.
First onsen trip? Start with planning your first onsen trip and onsen etiquette. Want a bath to yourself? See private onsen baths. Curious about the old mixed baths? See mixed bathing in Japan.