If you're planning a trip to Japan, there's an authentic experience you simply can't miss—a cultural staple in Japan: onsen and sentô baths.
What’s the difference between onsen and sentô?
Before understanding why these baths are so popular, it's important to distinguish between onsen and sentô, two common types of public baths in Japan:
Onsen (温泉)
An onsen is a bath fed by a natural hot spring. To be officially recognized as an onsen, the water must come from a geothermal source with a minimum temperature of 25°C. In practice, the Japanese generally consider a good onsen to be over 40°C.
Additionally, the water must contain specific minerals—at least one of the 19 chemical elements identified by the Japanese government, such as sulfur, iron, calcium, sodium, or magnesium. These minerals give each onsen unique therapeutic properties.
Traditional Japanese inns (ryokan) often feature onsen, and there are also standalone facilities dedicated to them.
Sentô (銭湯)
In contrast, sentô use ordinary water, which is heated artificially to between 35°C and 40°C.
Sentô used to be very common because many Japanese homes didn’t have private bathrooms. Nowadays, sentô are less prevalent but still serve as social hubs where locals unwind after a day of work.
We particularly recommend the APA hotel chain, which is known for offering sentô in some of their locations at affordable rates. After a long day of exploring, we love visiting the sentô rather than using the bathroom in our hotel room.
Why visit an onsen?
A purification and relaxation ritual
Onsen aren’t just about relaxing in a hot bath. In Japan, soaking in an onsen is a purification ritual, and it’s essential to wash thoroughly before entering the water.
Rotenburo, or outdoor baths, are especially popular for their serene setting, offering an instant connection with the surrounding nature.
Health benefits from mineral-rich waters
The therapeutic properties of onsen are another reason they’re so appealing. Each onsen is unique, depending on its mineral composition, which can help relieve muscle pain, improve circulation, or treat certain skin conditions.
Sulfur-rich onsen, such as those in Noboribetsu on Hokkaidô, are known for helping with rheumatism and skin issues. Others, rich in iron or sodium, are recommended for improving circulation and relaxing muscles after an active day.
Why visit a sento ?
A glimpse into local life
While onsen often attract tourists, sentô are frequented by locals. Visiting a sentô gives you a glimpse into everyday Japanese life. These humble establishments are places where residents come to relax and socialize after a long day.
In traditional neighborhoods of Tôkyô like Yanaka or Asakusa, it’s not uncommon to find classic sentô. These facilities, often adorned with murals of landscapes such as Mount Fuji, offer a retro and friendly ambiance.
A traditional bath evolving with the times
Although the number of sentô has decreased in Japan, some continue to thrive by blending tradition with modernity. Some bathhouses now offer additional services like saunas or whirlpools. Thermae-Yu in Shinjuku or Spa World in Ôsaka are examples of modern sentô that combine the charm of traditional public baths with contemporary comforts.
How to prepare for a visit to onsen and sentô ?
For a detailed guide on what to expect when visiting an onsen or sentô, you can refer to our full guide. Below are some key points:
Etiquette rules to follow
To ensure a smooth visit, it’s important to observe the following rules:
- Wash before entering: Clean yourself thoroughly before getting into the bath. This ensures the water stays clean for everyone.
- Nudity is required: Bathing is done completely nude, though men and women are separated into different baths.
- Tattoos may be restricted: In many places, tattoos are frowned upon due to their historical association with the Yakuza. However, some modern onsen and sentô now accept tattooed guests or offer cover-up patches.
What to bring
Onsen and sentô provide all the essentials for bathing, but depending on the facility, you may want to bring your own towel:
- Larger onsen and sentô often include towels in the entrance fee.
- Smaller establishments may offer towels for rent.
- At small neighborhood sentô, you’ll need to bring your own, along with your soap and shampoo.
Where to find the best onsen and sentô in Japan ?
The top onsen destinations
- Hakone (near Tôkyô): Popular with tourists for its proximity to Tokyo and breathtaking views of Mount Fuji.
- Beppu (Kyûshû): Famous for its numerous hot springs and variety of baths, including mud baths and hot sand baths.
- Kusatsu (Gunma): Renowned for its sulfur-rich, very hot water, considered some of the best in Japan.
Traditional sentô to experience
- Sakura-yu in Tôkyô: A retro-style sentô in the Yanaka district.
- Funaoka Onsen in Kyôto: Despite the name, it’s a historic sentô with wooden baths and traditional architecture.
