Japan has over 3,000 designated hot spring (温泉, onsen) areas and more than 25,000 individual onsen facilities — from multi-floor resort ryokan to roadside day-use bath houses and neighborhood sento-onsen hybrids. For residents, onsen shifts from tourist experience to regular wellbeing practice — a weekly or monthly ritual that restores both body and mind in ways specific to Japan’s volcanic geology and bathing culture.
Types of Onsen
- Rotenburo (露天風呂) — outdoor onsen bath; the classic image of Japan’s hot spring culture; rock-edged pools set in forest, cliff, or garden environments. Premium experience at most ryokan and resort onsen.
- Uchiyu (内湯) — indoor onsen bath within a ryokan or facility
- Ashiyu (足湯) — free foot-soaking baths in outdoor public spaces; common in onsen towns and train stations. Accessible and clothing-on.
- Day-use onsen (日帰り温泉) — facilities accepting non-staying visitors for bathing, typically ¥500–2,000/person. Often include changing rooms, lounge areas, and restaurants.
- Super sentō (スーパー銭湯) — large-format commercial bath facilities with multiple indoor and outdoor pools, sauna, restaurant, and relaxation area; urban and suburban; ¥800–1,500; not always natural spring water but highly popular for regular use.
Water Types and Therapeutic Properties
Japan’s onsen are classified by water chemistry, each with specific claimed therapeutic properties:
- Simple spring (単純温泉) — mild, suitable for all; common throughout Japan
- Sodium chloride (食塩泉) — warming effect; relieves fatigue; common in coastal areas
- Sulfur (硫黄泉) — distinctive egg smell; skin-softening; antimicrobial. Beppu, Noboribetsu, Kusatsu
- Bicarbonate (炭酸水素塩泉) — “beauty water” (美人の湯); skin-smoothing; Hakone, Izu
- Acidic (酸性泉) — strong antibacterial; not suitable for sensitive skin or open wounds; Kusatsu, Zao
- Radioactive radium spring (放射能泉) — mild radioactivity claimed for joint conditions; Misasa Onsen (Tottori)
Onsen Etiquette
Onsen etiquette is consistent across facilities:
- Wash and rinse thoroughly at the shower stations before entering the shared bath — this is non-negotiable
- Do not bring towels into the onsen water — fold your small towel on your head or leave it on the side
- No swimming, splashing, or loud behavior in the bath
- Keep long hair tied up or out of the water
- Drink water before and after — onsen dehydrate; most facilities have water stations
- Do not drain the bath or add cold water without asking — temperature is communal
The Tattoo Question
Many traditional onsen facilities prohibit tattoos due to historical association with yakuza and concern about other guests’ comfort. This policy is the single most common source of frustration for foreign residents with tattoos. The landscape is changing: many facilities now have private baths (貸切風呂, kashikiri buro) that can be reserved regardless of tattoo status; some facilities have explicitly become “tattoo-friendly” (タトゥーOK); and younger operators in tourist-heavy areas have relaxed policies. Research ahead or call/email to confirm policy. Search “タトゥーOK 温泉 [your area]” for current options.
Day-Trip Onsen from Major Cities
- From Tokyo: Hakone (1.5 hours), Atami (50 minutes), Nikko (2 hours), Ikaho/Kusatsu (2–3 hours)
- From Osaka/Kyoto: Arima Onsen (1 hour from Osaka), Kinosaki Onsen (2.5 hours), Shirahama (2.5 hours)
- From Nagoya: Gero Onsen (1.5 hours), Yuageshima (1.5 hours)
- From Fukuoka: Beppu (1.5 hours), Yufuin (1.5 hours), Unzen (2 hours)