A Beginner's Guide to Japanese Onsen and the Art of Bathing

What is an onsen?

Onsen can be indoor or outdoor, natural or developed. Photo: dryadphotos/Shutterstock

As Japan has extreme seismic activity and islands amid four major tectonic plates, it’s no surprise that the country has an estimated 27,000 hot springs. Hot springs result when magma heats subterranean water that seeps to the surface through cracks created by volcanoes, earthquakes, and other shifting of the plates. Hot springs are often rich with minerals carried from their contact with rocks on the way back to the surface. In Japan, hot springs are called onsen, whether they’re totally natural or developed into baths and luxury resorts. They’re basically the same as hot springs in the US, scientifically speaking.

Japanese culture has taken advantage of the soothing and therapeutic benefits of onsen for millennia. It remains such an integral part of the culture that in 1948, the government passed a national act (Onsen Hō) establishing requirements for the minimum temperature, depth of the source, and minerality of the water to be legally called an onsen – which means businesses can’t just heat a pool, slap up a sign, and advertise that they’re running an onsen. The ♨ symbol on a map or hotel indicates an on-site onsen.

Hot spring sources are scattered all over the country, with around 3,000 official onsen in the country. You’ll find them in hotels and resorts, ryokans (traditional inns), and national parks, and some people are lucky enough to have them in their homes. If you’re in Japan, visiting an onsen is a perfect way to steep yourself (literally) in Japanese tradition.

“Bathing is one of the most common practices and one of the most communal parts of life in vacations in Japan,” says Sam Goold, Japan Specialist at Red Savannah, which sells vacation packages to Japan. “Embrace it as part of getting under the skin of the culture.”

In addition to the official laws, there are generally unbendable unwritten rules and best practices locals and visitors alike must follow before starting to onsen (and yes, you can use it as a verb).

What to wear to an onsen

There’s no need to be self-conscious — everyone is naked at the onsen. weniliou/Shutterstock

Leave your inhibitions – and your street clothes – at the door. The ritual of onsen is done naked. Period. You do not wear a swimsuit in an onsen, and no, you can’t leave on any underwear. Any clothing could introduce dirt, bacteria, lint, and laundry detergent to the water, negating the whole point of soaking in purified, beneficial spring water. Remove your shoes before entering any Japanese onsen, and put your clothes and belongings in a locker or basket. Depending on the facility, you may want to keep anything particularly valuable locked away, including your phone – this isn’t the place to film an Instagram reel.

Don your yukata correctly

If given a yukuta, make sure to put the left side over the right. Photo: Bhakpong/Shutterstock

One thing you will see many people wear at an onsen is a yukuta, a lightweight cotton or linen robe similar to a kimono. If you’re popping around from hot spring to hot spring in a public park or, in our case, around a hotel, you’ll likely be given one to wear. Our Ryokan staff delivered various yukatas in floral and other patterns to our room in a neatly folded pile, along with a handy guide on how to get dressed for onsen. Yukata are easy to wrap and tie with a belt, but there is one very important detail to remember: be sure to fold the left side over the right side, as the opposite is reserved for dressing the recently deceased.

Visible body art, like tattoos, might not be allowed

The smaller and more discreet your tattoo, the less likely it is to be a problem. Photo: nuchao/Shutterstock

Japan has a fraught history with tattoos, as they’re historically linked to the Yakuza, or Japanese mafia. Though it’s changing, traditionally, showing your tattoos in public wasn’t allowed. Even those who engage in the traditional tattoo practice of tebori (a traditional tattoo method done by hand, rather than with a gun) will often choose locations on thir bodies usually covered by clothing.

Since my older kid has many tattoos on their arms, and I have small ones on my forearm and ankle, we were concerned that we’d be banned as tattoos in onsen are normally a no-go. I reached out to our hotel onsen in advance to check the policy and learned we’d be permitted to use the onsen without covering up our art. Public facilities might not be as forgiving, though, so it’s best to check in advance. You can sometimes cover up your tattoo for onsen with waterproof tape or BandAids. Very small and discreetly placed tattoos, especially among foreigners, may be more likely to be forgiven.

Onsen is (usually) a single-gender activity

Most public onsen are divided into make and female sides. Photo: Tom Wang/Shutterstock

While there are some Japanese onsen that permit all genders to bathe together, usually, onsen are divided into separate areas for men and women. My older kid is nonbinary, but was hesitant about bathing with strangers anyway, so they opted out. But if you’re non-binary, transgender, or gender fluid and want to use a public onsen, you’ll probably have to choose your gender assigned at birth. The different sides are divided by curtains, usually blue for men and red for women. For onsen users who aren’t comfortable with the single-gender system, renting a private onsen can be a good alternative.

Showering etiquette is non-optional

Be sure to sit and rinse before getting into a shared onsen. Photo: Chatchawat Prasertsom/Shutterstock

Showering is the first thing you should do upon entering any Japanese onsen, even if you just showered in your hotel room. The other bathers don’t know this, and showering shows you respect your fellow onsen-goers.

“This is not just common practice, but also courtesy,” Gould said. “Hygiene is taken very seriously.”

As I entered my first onsen, I saw the typical row of handheld showers on the wall, with small wooden stools to sit on while washing up, as standing is considered bad manners. You’ll be given two towels at most onsen; the small one is for washing before soaking, and the larger one is for drying off post-soak. There’s no need to dry off after showering since you’re headed directly into the hot water. And on that note – don’t immerse your hair in the onsen. You’ll see men and women with their small towels on their heads. This is both to keep the towel out of the water, and to make sure you don’t mix your small towel up with someone else’s.

There may be a workaround to some of the logistical challenges

Booking a private onsen session may be best for travelers not comfortable with the two-gender system of a traditional onsen. Photo: Thomas Morris/Shutterstock

In addition to the single-gender onsen, our hotel had a small, private onsen available to rent by the hour. Some upscale resorts and ryokans may have private onsens in some rooms. This can solve the issue of visible tattoos and bathing with strangers, though since it’s still a communal bath, you’ll need to follow the honor system and enter naked. Mixed-gender families or groups who feel comfortable soaking together can do so, or you can book separate sessions, or divide the time. And don’t do anything in the onsen other than soak.

Not all the pools are hot

Photo: nieriss/Shutterstock

The geothermal-fed baths are the main draw, and since these can be very hot, it’s recommended to soak for no more than 30 minutes. And honestly, I could barely stay in for half that time.

I was pleasantly surprised to find a waterfall inside a shallower pool that was tepid; an outdoor, free-form and rock-lined bath that was very warm but not hot; and a long, rectangular pool outfitted with small river rocks and filled several inches deep with frigid water, designed to mimic the Scandinavian bath concept. “Many onsen provide options to go from hot to cold, allowing the body to cool off and repeat the process, enabling a longer and more enjoyable experience,” explains Marc Letourneau, general manager for Club Med East Asia, Japan & South Korea. But don’t equate these cooler spots for pools. “Putting your head under water, splashing, playing, or swimming is not appropriate,” he says.

Onsen etiquette may be to skip the post-soak rinse

Depending on the onsen, you may not need to shower after your soak. Photo: Daniel Beckemeier

Even though it might feel natural to rinse off, the water may be rich with minerals. Silica smoothes and softens skin, calcium carbonate enhances your skin’s defense against harmful UV rays, and magnesium and potassium can boost cellular regeneration. But after visiting onsen with acidic water or pools with a high sulfur content (which usually have some odor), you’ll want to shower afterward. The easiest way to tell what to do may just be to see if the people who get out before you shower or not.

Choose the right time of day

Photo: zmkstudio/Shutterstock

We still felt quite full from our large dinner on a traditional tatami mat as we were heading to our private onsen. While the soak was still enjoyable, it probably would have been more so if we had been able to book a slot before our meal.

The next morning, I went to the public onsen immediately after waking up, and sitting in the outdoor onsen while watching the sunrise and listening to birds chirping was the perfect start to a day of sightseeing around Mount Fuji. Since onsen can do wonders for muscle aches, potentially lower stress-inducing cortisol, relieve fatigue, and increase circulation, it can also be an amazing antidote to jet lag. So the first thing you may want to do when you arrive in Japan is jump in the nearest onsen.