A run-down of some of the features and bath types that you will find in the bathing areas of the onsen facilities.
Usually the first thing you’ll see when you enter the bathing area. Yu (湯) means hot water and kake (かけ) means put on or throw—so this is the water that you dowse your body with before you enter the baths. Many opt to wash themselves in the showers instead, but in any case you should cleanse your body before you enter the baths.
The bathtubs at the onsen and sento are not for cleaning your body; they are for relaxing and soothing the body aches of a long day. You should cleanse yourself in the shower areas before entering the bathtubs. You will always find a line of showers (sometimes with separators, more often without) when you enter the bathing area. In front of the showers you will have a small basin (for shaving) and a stool. Japanese wash themselves while seated, although you do find standing shower cubicles in some onsen. Just about all onsen provide body wash, shampoo, and conditioner in the shower area.
Literally, open-air bath, rotenburo are really what make bathing at the onsen in Japan so special. Most onsen will have a rotenburo, but the onsen out in regional Japan have the luxury of magnificent views and
Same sort of thing as a Jacuzzi—bubbles fire up from different angles at your skin. Fairly common in the onsen, although less so at the more traditional establishments.
Ever wanted to bath in warm sparkling water? Well, now you can. The carbonated water is supposed to help with circulation.
Nekorobi are not baths as such; they are stone slabs over which warm onsen water trickles. You lie supine (usually with a raised stone for a pillow), and relax while looking up at the sky (the constant stream of water keeping your body from getting cold).
Japanese cypress, hinoki cypress or just hinoki is a species of Cypress native to Japan. It is highly resistant to rot and is lemon-scented—the perfect wood from which to make a bathtub.
Tsubo-yu are often found at the onsen (usually outside). They are one-man pot tubs into which hot spring water constantly flows (and overflows). You can either squat down inside or, if you really want to show you’re an onsen lover, lie in with your arms and legs dangling out at the side.
This one is a bit more of a rarity. It’s a tub (or an area of a tub) which pulsates with an electrical current. Bathtubs and electricity are not normally two things that go hand-in-hand, but the denki-buro won’t give you a shock—it just produces an intermittent frizzling sensation on the skin like static electricity. If you’re interested, Yumori no Sato has an electric cave in its main open-air bath.
This one is pretty obvious. Some onsen scent the water of bathtubs or put flowers, petals, and even fresh fruit into the water. Not seen so often, but they’re out there.
A bit like a jet bath or Jacuzzi, but with very fine bubbles that turn the water white and feel like—you guessed it—silk on the skin.
A goemon pot is a type of wooden pot tub that gets its name from Ishikawa Goemon, an infamous outlaw in the Edo period who was boiled alive in one for his crimes.
Not much explanation needed here, but the sauna at the onsen come in all different forms. The family-orientated onsen will often have televisions fitted with a tiered seating system so that everyone is facing the screen. The more traditional onsen will keep things simple and let you sweat in peace.
Dry saunas are typically 80-100°C with a humidity around 10%. Mist saunas, on the other hand, are set at a much lower temperature (around 40°C) but with a humidity closer to 100%. As a result they are less harsh than the typical dry saunas and more often found in the female onsen.
If the onsen has a sauna, then it will almost always have a mizuburo (“cold water tub”). The temperature is usually around 17-20°C and you are supposed to get in after a stint in the sauna to cool the body down, but remember to wash away the sweat from your body in the shower area or by using the kake-yu before you do so.