Japan has over 27,000 hot spring sources and a bathing culture stretching back over a millennium. For residents, onsen are not just tourist attractions — they’re a regular part of life for millions of Japanese people. This guide covers everything from etiquette to types of baths to the best destinations around Japan.
Onsen vs. Sento: Understanding the Difference
- Onsen (温泉): Natural hot spring water with specific mineral content as defined by Japanese law. The water source is natural.
- Sento (銭湯): Public bathhouse using regular heated water. Traditional neighborhood facilities, usually cheaper than onsen.
- Super sento (スーパー銭湯): Large commercial facilities that may include both natural and non-natural baths, plus amenities like restaurants, massage, TV lounges.
Essential Onsen Etiquette
Onsen bathing has rules that exist for hygiene, comfort, and respect for other bathers:
- Wash before entering: Use the shower/wash stations (カラン karan) with soap and shampoo before getting into any bath
- No swimwear: Communal onsen are always nude. Swimwear is only appropriate in mixed-gender (混浴 konyoku) outdoor baths at some facilities.
- Small towel management: You bring a small modesty towel (手ぬぐい tenugui or small towel) — keep it out of the water; fold it on your head or set aside
- Don’t submerge your head: Hair should be tied up and kept out of the water
- Be quiet: Onsen are relaxation spaces — keep conversation low, avoid splashing, no phones in bath areas
- Hydration: Onsen, especially hot ones, can cause light-headedness — drink water before and after, don’t stay in too long initially
Tattoo Policies
Many traditional onsen facilities prohibit tattoos due to historical associations with organized crime. This affects foreign residents with tattoos — options include:
- Private baths (貸切風呂) — rented for a set time, available at many ryokan and some public facilities
- Tattoo-friendly facilities — some facilities explicitly welcome tattooed guests; search for 入れ墨OK or タトゥーOK
- Accommodation with in-room baths — ryokan with private en-suite baths
Types of Onsen by Mineral Content
Different mineral compositions are associated with different therapeutic properties (though individual results vary):
- Simple thermal (単純温泉): Gentle, low mineral content — suitable for sensitive skin and beginners
- Sodium chloride (塩化物泉): Salt-based, warming, said to help with chronic pain
- Sulfur (硫黄泉): Strong smell, milky white — associated with skin benefits and respiratory conditions
- Carbonated (炭酸泉): Bubbling effect, often cooler temperature — said to be good for circulation
- Iron (含鉄泉): Orange-red color due to iron content
Rotemburo: Outdoor Baths
Rotemburo (露天風呂) — outdoor hot spring baths — are considered the pinnacle of the onsen experience. Bathing in steaming water surrounded by mountain scenery, snow, or autumn foliage is a quintessential Japanese experience. Most ryokan have both indoor and outdoor baths; the outdoor baths are usually the highlight.
Best Onsen Destinations for Residents
- Hakone (神奈川): Easy day trip from Tokyo; volcanic area with multiple onsen towns and ryokan — excellent for first-timers
- Kinosaki Onsen (兵庫): Charming historic town with 7 public bath houses (外湯 sotoyu) — the classic onsen town experience; guests walk between baths in yukata
- Noboribetsu (北海道): One of Hokkaido’s premier onsen towns; dramatic volcanic valley setting (地獄谷 Jigoku-dani)
- Beppu (大分): Japan’s highest volume of hot spring output; famous “Hells” (地獄 Jigoku) are colorful non-bathing display pools
- Kusatsu (群馬): One of Japan’s most famous onsen towns; distinctive yumomi (water stirring) tradition and strong acidic waters
- Dogo Onsen (愛媛): Japan’s oldest hot spring facility; the building reportedly inspired the bathhouse in Spirited Away
- Arima Onsen (兵庫): Japan’s oldest onsen, accessible from Kobe; two distinct water types (gold and silver)
Day-Use Onsen for Residents
You don’t need to stay overnight to enjoy onsen. Many facilities offer 日帰り入浴 (hi-gaeri nyuyoku — day-use bathing). Entry fees are typically ¥500–2,000. Super sento facilities are more accessible for regular use — often near suburban train stations, open late, and reasonably priced with good amenities for an evening after work.
Incorporating onsen into regular life — even just a local sento occasionally — is one of the most culturally rewarding aspects of living in Japan.