Crash Course: Onsen

Since moving to Kyushu over a year ago, I’ve made onsen-hopping my new (although only occasional) pursuit. In a country with an abundance of volcanic activity, it seems there’s always a hot spring around every corner. So what do you need to know to enjoy one of Japan’s best natural features? Read on and see.

Onsen is the Japanese word for “hot springs” and, just like in any other country, you’ll find them clustered in areas of volcanic or geothermal activity. Japan being located on a highly volatile fault line that causes its share of volcanic eruptions, it should come as no surprise that there are onsen spread across the archipelago from Hokkaido in the north to Kagoshima on the southern tip of Kyushu. (It shocked me to learn at the time, but the Okinawan islands are not volcanic in origin. Rather, they’re the result of millenia of coral deposits building up. There is only one known natural hot spring in the prefecture and it’s located on one of Okinawa’s minor outlying islands.) If you’re looking for onsen on a map, it’s nearly always represented by this symbol – ♨.

For a hot springs to be technically classed as an onsen, the water must contain at least one of 19 specific chemical elements and be naturally 25°C (77°F) or warmer. Most onsen in japan boast about one healing property or another, whether it’s relief from indigestion or a guarantee for better skin. I can’t claim to have been miraculously cured of any ailments at a Japanese onsen, but I certainly do enjoy the feeling I have after a stint in the baths.

Rotemburo baths at a riverside onsen ryokan
Rotemburo baths at a riverside onsen ryokan

Many onsen are attached to a ryokan, or traditional inn (hence the term onsen ryokan). Onsen ryokan often offer outdoor baths (known as rotemburo)  in some sort of attractive natural setting, such as next to a river or deep in the forest. These rotemburo can be separated by gender (one set of baths for men, another for women) or mixed. Only on a rare occasion will a mixed outdoor onsen require bathing suits. Normally, it’s birthday-suit only. In some ryokan, the staff will switch the baths around every morning – the women’s bath becomes the men’s bath and vice versa. Don’t panic if you forgot what the staff told you – blue (for men) and red or pink (for women) curtains are hung in front of the entrance to each bath so you shouldn’t have any doubts as to which one you should be entering!

Entrance to an onsen in Odaiba - men and women go separate ways just after the curtain
Entrance to an onsen in Odaiba – men and women go separate ways just after the curtain

In some areas of Japan, the hot springs are so abundant that a resort town will grow up around the waters. Some of these towns can be pretty charmless, full of boxy modern ryokan hotels and clogged with tour buses transporting hordes of visitors. Atami Onsen on the Izu Peninsula below Tokyo, Kinugawa Onsen north of Tokyo, and Beppu town in eastern Kyushu are some of the more concrete, developed onsen resorts in Japan. There is nothing wrong with their baths, of course, but the towns themselves lack a bit of soul. If you are searching for that quintessential “back-to-nature” onsen resort, you might be better off at Nyuto Onsen in Akita prefecture, Shuzen-ji Onsen on the Izu Peninsula, or Kurokawa Onsen in my own backyard of Kumamoto.

The hot springs resort of Noboribetsu Onsen in Hokkaido
The hot springs resort of Noboribetsu Onsen in Hokkaido

Don’t be confused and equate a regular ryokan bath with an onsen bath. Many ryokan maintain bathing facilities (gender separated) that are often blessed with beautiful cypress tubs or garden locations. These baths are lovely and well-maintained, but the water is not from a natural hot spring source. Still, the same bathing rules apply at both hot spring and regular baths – soap up and rinse off outside of the tubs or pool first and then enjoy a nice relaxing soak.

7 thoughts on “Crash Course: Onsen

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  1. I’m a big fan of Gero Onsen here in Gifu Prefecture, which is considered to be one of Japan’s three best onsen towns. I also really love the onsen up in the Hida region of Japan (Japan Alps) and Nagano.

    1. I haven’t been to Gero Onsen yet but I’ve heard good things about it. I would love to get back to the Hida region in general sometime soon, and a trip to an onsen there would be a nice addition!

    1. After a second trip up there this past weekend, I can definitely say that I will be heading back to Kurokawa Onsen again and again until I have tried all of the baths there! It really is such a quiet, secluded place.

  2. Last year during my first time in Japan I’ve been near Kawazu, Izu Peninsula. Along the inland way to Shuzen-ji (where I’ve been the day after) I spent the night in a ryokan built on Seven Waterfalls, where you can find a fantastic mixed rotenburo surrounded by a wood and mountains, with a huge amount of stars in the sky… my lovely first time in a onsen!

      1. You’re right! The ryokan was called Amagiso, anyway you require to wear bathing suits only during the day, cause of on the other side there is a road for people visiting the waterfall and the baths are not covered. But the funny “receptionist” told me and my girlfriend to go there naked after night falls.

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