Japan has over 3,000 onsen resorts. Soaking in a natural hot spring is one of the great pleasures of living here — and one of the most intimidating experiences for first-timers. The rules are unwritten, enforced by silence, and foreigners get almost no guidance. Here’s exactly what you need to know.
What Is an Onsen?
An onsen (温泉) is a natural hot spring bath fed by geothermally heated water. It’s different from a sento (銭湯), which is a public bathhouse using regular heated water. Onsen have mineral-rich water with specific health properties depending on the source.
Most onsen are gender-separated (men’s and women’s baths). Some have rotemburo (露天風呂) — outdoor baths.
The Golden Rules Before You Get In
1. Wash Thoroughly First
This is non-negotiable. Every onsen has a washing area with individual stations (small stool, bucket, shower, soap, and shampoo). Sit on the stool, use the handheld shower, and clean your entire body before entering the bath.
Do not enter the onsen without washing first. This is the most important rule.
2. No Swimwear
Traditional onsen are completely nude. Swimwear is not allowed — it’s considered unsanitary. The only exception is some modern “onsen theme parks” that provide swimwear areas, but these are not traditional onsen.
3. Towel Stays Out of the Water
You’re given a small modesty towel. You can use it to cover yourself while walking around, but it must not go into the bath water. Fold it and place it on your head or the side of the bath.
4. Tie Up Long Hair
Hair should not touch the water. Tie it up or use the small towel to keep it away from the surface.
5. No Loud Talking or Phones
Onsen are places of relaxation. Keep your voice low. Absolutely no phones or cameras — taking photos in an onsen is a serious violation of privacy and will get you asked to leave immediately.
6. Rinse Before Re-entering
If you get out to cool down, rinse off at the shower station before getting back in.
The Tattoo Question
Many onsen still ban tattoos. This is changing slowly, but the majority of traditional onsen and ryokan maintain this policy. The historical association between tattoos and yakuza (Japanese organized crime) is the reason.
Your options if you have tattoos:
| Option | Details |
|---|---|
| Private bath (貸切風呂) | Book a private onsen room — no rules on tattoos |
| Tattoo-friendly onsen | Search specifically for 「タトゥーOK」onsen |
| Cover with waterproof tape | Some onsen allow small tattoos covered with skin-colored patches |
| Ryokan with in-room bath | Many ryokan rooms have their own onsen — no other guests |
If you’re unsure, call ahead and ask. It saves embarrassment.
Step-by-Step: Your First Onsen Visit
- Pay at the front desk and receive a towel set (or bring your own)
- Change in the locker room — store everything in a locker
- Enter the bath area carrying only your small towel
- Sit at a washing station and clean your entire body thoroughly
- Rinse the station when you’re done (leave it clean for the next person)
- Enter the bath slowly — the water is hot (typically 40–43°C)
- Soak quietly, keep the small towel on your head or to the side
- Get out, rinse, and repeat as desired
- Dry off in the changing room before returning to the locker area
Onsen Temperature Guide
| Temperature | Experience |
|---|---|
| 38–40°C | Lukewarm — gentle, good for beginners |
| 40–42°C | Standard — most common |
| 42–44°C | Hot — experienced bathers |
| 44°C+ | Very hot — short dips only |
If you feel dizzy or overheated, get out immediately and cool down.
Mixed-Gender Onsen (Konyoku)
Some traditional onsen have konyoku (混浴) — mixed-gender baths. These are becoming rare. The etiquette:
- Women often wear a thin cotton cloth (yukata or bathing cloth) provided by the facility
- Men are usually expected to be nude or can wear trunks if provided
- Noise and staring are completely unacceptable
Onsen vs. Sento: Which Should You Try First?
Sento (銭湯) are easier for beginners — the water is regular heated water, they’re cheaper (¥500–¥600), and staff are more used to confused foreigners. Same basic etiquette applies.
Once you’re comfortable with sento, onsen is the natural next step.
Common Mistakes Foreigners Make
- Walking into the bath without washing (immediate side-eye from everyone)
- Taking a phone out near the bath area
- Speaking loudly or splashing
- Leaving the shower station messy
- Forgetting to cool down between soaks — heatstroke is real