The Standard Onsen 【温泉：おんせん】
Onsen, meaning hot springs, would be the most commonly known type of spa in Japan.
The definition is simple:
An onsen either
(1) is above 25°C (77°F) in its natural state flowing out from the ground or
(2) contains a certain amount of particular mineral.
Want to see the full definition? The Japan Spa Association Hot Spring of Japan has a detailed definition of what substances may be contained in a hot spring here
. So, any place that has a certain type of hot spring that meets the condition above can be called an onsen! Places like public baths sometimes have onsens, but a lot of the times, they are just ordinary baths - they don't meet Japan's strict definition!
The top three onsens in Japan said to be the Arima Onsen (in Hyogo), the Kusatsu Onsen (in Gunma), and the Gero Onsen (in Gifu). If you're in Japan, you might want to try a hot spring at least once!
Go Outdoors! The Roten-buro【露天風呂：ろてんぶろ】
"Rotenburo" simply means a bath located outside. It could be just a normal bath, or it could be an onsen.
The best part about this is that you get to feel the seasons and enjoy nature while you are bathing. In many cases, places that offer indoor spas also have a rotenburo as well. Just like this one
in the Unazuki area in Toyama.
What part of Japan has the most famous outdoor onsen?
That depends on if you want to choose based on the quality of the spa, or you prefer the scenery, or if you care about other things altogether. But Japanese spa-ranking websites often say that Kinugawa
onsen comes third place, followed by Ito onsen, and finally Atami onsen.
The Public Baths: Sento【銭湯：せんとう】
Public baths (sento) are easier to access, as there are also many of them in major cities. Here are a few lists of sento by city (in Japanese) for those who would like to explore the world of public baths.
- Tokyo Sento Map
The difference between a sento and an onsen is that sento are just public baths, while onsen are natural hot springs and contain particular minerals. We've described the differences between a sento and an onsen in more detail here
, so if you would like to know any details take a look!
There are also what are called "Super Sento", where they offer more services than just baths. For example, we've been to an onsen theme park in Chichibu, Saitama
with shops and food courts located within the same venue. This website called Supersento.com
allows you to search through all the super sentos in Japan.
Stay over a night: The Ryokan 【旅館：りょかん】
The ryokan is a type of a traditional inn in Japan, and a lot of the time they feature rooms with tatami mats and communal baths - usually a natural hot spring. The benefit of going to a ryokan is that you get to relax and enjoy your own private room after you finish your bath, enjoy local specialty meals, and just sleep when you want to. (Just like our experiences in Tendo
or Unazuki in Kurobe
All to yourself: The Kashikiri 【貸切：かしきり】
If you don't really want to share a bath with others, don't worry, there's an option for you too! If you get a kashikiri
bath, meaning a private rental, you can enjoy a nice private bath time all to yourself, or just share that experience with your family. Some ryokans offer this service, or even have private baths built into the balcony of guest rooms.