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Hot Spring Information

Hot Spring Information

In Japan, hot spring baths are known as “onsen!” Just like in many other places in the world, onsen are bathhouses that use water from natural springs. Anyone can tell you that having a soak in a nice warm bath is very relaxing, but onsen water is usually filled with a variety of natural minerals that can have medicinal and therapeutic effects, as well.
Every onsen page on the website features a helpful table briefly outlining such details as the water type, bath facilities, and available amenities. Information explaining those details is included here on this page, below!

Onsen Information Table Explained

Spring Type

This will tell you what type of spring it is, in terms of mineral composition. You can read about the various spring types further below.

Mixed Bath

This will tell you whether the onsen is gender-segregated.  “No” means the bath is separated into men-only and women-only sections, “Yes” means it is a non-segregated bathhouse, and “Both” means that there are both segregated and non-segregated baths.


This will tell you whether the onsen provides towels for drying off. “Yes” means the onsen does provide towels as part of the price of entry, to be returned once you leave. “No” means you will need to bring your own towels. “Available” means that towels are available, either for purchase or rental. Note that this information is specifically for the purpose of those visiting the baths and not staying overnight; many onsen are part of larger hotels or inns, and guests staying in rooms will frequently have towels provided to them that they can bring to the onsen.

Bath Towels

This will tell you whether the onsen provides bath towels/wash rags for cleaning yourself. “Yes” means the onsen provides them as part of the price of entry, to be returned once you leave. “No” means you will need to bring your own. “Available” means that towels are available, either for purchase or rental. As with towels, bath towels may also be provided to those staying in rooms at the onsen.


Every onsen typically provides at least body soap and shampoo. Some provide additional things such as conditioner and facial soap. If you plan to bring your own toiletries, you don’t need to pay much attention to this.


Many onsen provide a variety of small amenities to enhance the experience. Hair dryers are common, as are stations for drinking water (to get re-hydrated after a sauna, for example). Some onsen will also provide combs and toothbrushes.

Indoor Bath / Outdoor Bath / Sauna

Not all onsen have an outdoor, or open-air bath. Similarly, some lack saunas, or only have outdoor baths. Plan accordingly!

Spring Types

Simple (単純泉)

Simple springs can be thought of as a “standard” type of onsen. They may have a mix of minerals, but feature no particularly outstanding properties. This can be beneficial in its own way, however, as it means the water will be very mild on your skin and body, making it a safe choice for people of all ages.

Sulfur (硫黄泉)

You’ll likely smell a sulfur spring well before you see or set foot in it, as their strong odor (akin to rotten eggs) is one of their most recognizable characteristics! Sulfur is one of the most classic types of natural hot spring, and ever since ancient times the water from this type of spring has been said to have a wide variety of beneficial health effects. Most notably, the milky waters of these springs can help with various skin problems such as acne and dermatitis, as well as gynecological problems and diabetes.

Simple Sulfur (単純硫黄泉)

As one of the most common types of natural springs in Japan, sulfur springs can actually be organized into a large number of categories based on their precise mineral and chemical composition. Simple sulfur is one of the two broadest categories of sulfur spring, and refers to those which completely lack hydrogen sulfide, the key ingredient behind a sulfur springs’ characteristic odor. This makes simple sulfur springs a good choice for people who seek some of the wide benefits of sulfur springs but don’t enjoy their strong smell.

Chloride (塩化物泉)

Chloride springs are characterized by high sodium levels. The water will often have a milky quality to it, and the way it coats your skin tends to have a moisturizing effect while also sealing in warmth. These types of springs will warm you up even more than the average onsen will, which makes them a strong choice during winter.

Hydrogen Carbonate (炭酸水素塩泉)

Hydrogen Carbonate springs are frequently referred to as “Bijo-no-Yu”, or “Beauty Springs,” because the waters in them are typically said to promote smooth, beautiful skin. This is particularly true for springs with a high alkaline content because of their ability to exfoliate and remove dead skin cells.

Carbonated (炭酸泉)

Carbonated springs look a lot like simple ones at first glance. Upon entering one, however, you’ll usually find your skin quickly becoming coated in many fine bubbles! The novelty of this aside, carbonated springs are considered to be highly beneficial for body circulation, leading to improved blood flow and general detoxification, among other effects.

Entering An Onsen

For the most part, onsen are very simple to use: you just enter, wash yourself, and relax! But there are a few things you should keep in mind when using onsen in Japan, which we’ve listed below:

1. No tattoos

Unfortunately, many onsen in Japan do not allow tattoos. This is because of the general perception of tattoos being worn by gangsters and troublemakers. Some onsen sell temporary patches you can use to cover up tattoos, but otherwise if you have ink, you may need to look elsewhere!

2. Everyone is naked!

Unlike in some western bathhouses, people don’t usually wear swimsuits or towels in onsen. The vast majority of onsen in Japan are gender-segregated, so you won’t have to worry about being seen by the opposite sex, but this is certainly something that can take some getting used to if you’ve never bathed around others before. Just remember that people are there to relax and unwind, not stare at each other, and you’ll be well on your way to enjoying onsen.

3. Always wash yourself before entering the bath proper

Like any bathhouse, part of the purpose of an onsen is to clean yourself. Every onsen you go to will have stalls lined with stools and shower hoses that you can use to give yourself a proper wash before getting into the bath. These stalls will typically have body soap and shampoo provided at the bare minimum, but it’s not unusual for people to bring their own bathing supplies. Whether you bring your own supplies or use those provided by the onsen however, remember that the only thing that should be entering the bath is your body! Don’t let your bath towel, for example get into the bath with you; keep it next to you on the rim, or perhaps on your head. It’s also not a bad idea to rinse yourself off again at the shower before heading back into the changing room, once you’re done in the bath.