Thanks to its overabundance of active volcanos, Japan is a veritable hotbed of hot springs. Warm, mineral-rich waters bubble up from beneath the earth all over the country, giving rise to spa precincts with charming ryokan (traditional Japanese inns). In small towns, the community gathers at bathhouses to chat, relax and wallow in geothermally heated water, as people did in ancient Rome.
To be classed as an onsen, an establishment’s water must contain at least one of 19 minerals, such as iron, sulphur or hydrogen carbonate, and be naturally warmer than 25 degrees Celsius. Generally bathing is done naked and often in gender-segregated baths (scroll down for etiquette tips). According to the Nippon Onsen Research Association, there are more than 3000 onsens in Japan. Here are some of our favourites.
The resort town of Takayu Onsen is perched halfway up the wooded slopes of Mount Azuma. The historic Tamagoyu ryokan (7 Machiniwasaka Takayu, Fukushima) is one of a cluster of bathhouses and inns that draw from numerous springs in the area. Tamagoyu has milky-blue water rich in hydrogen sulphide, giving it a distinctive sulphur smell – some people find it soothing; for others, it’s like rotten eggs. Irrespective of the odour, the water is known for being among the most therapeutic in the country. While you sit in the steaming, open-air tub, gaze out at the snow-covered woodlands. This is traditional onsen at its best.
Kurama Onsen is a half-hour train trip from the heart of Kyoto and is one of the few onsens in the area. The tiny spa is set amid leafy surrounds and has both indoor and outdoor baths. After a long day exploring the city or climbing to the Kurama-dera Mountain Temple, this onsen is a boon for sore feet and fatigued muscles. Kurama Onsen is also a ryokan so if things become too relaxing to consider a return to Kyoto, there’s food and accommodation right here.
The Hakone spa region in Kanagawa Prefecture is a mountainous district blessed with more than a dozen hot springs, thanks to the machinations of nearby Mount Fuji. The area, designated a Geopark by UNESCO, is about an hour-and-a-half from Tokyo by train, meaning daytrips are possible if you’re town-bound. Hakone Yuryo (4 Tonosawa, Hakone-machi, Ashigarashimo-gun, Kanagawa Prefecture) has gender-segregated onsens and a number of private baths for families or couples that wish to bathe together. There’s a free shuttle bus from Hakone-Yumoto train station every 10 to 15 minutes. Beware: Hakone Yuryo is tattoo-free (see “Cover your tattoos” below).
Located in the Ehime Prefecture on Shikoku island, the city of Matsuyama is known for its Dogo Onsen Honkan bathhouse, (5-6 Yunomachi-Dogo, Matsuyama) dating back to the Meiji period (1868-1912). Set in wooden, pagoda-style buildings, it’s the oldest onsen in the country, mentioned in Japanese literature 1300 years ago. The present structures were built in 1894 and were the inspiration for the bathhouse of the gods in the animated film Spirited Away. The main communal baths are open to everyone, while the Yushinden bath is reserved for the Imperial Family (it can be visited but not wallowed in). You can often see bathers wandering the streets in their yukata (a kimono-like robe common in onsens) after taking a dip.
Visitors cross a bridge over a crystal-clear stream to reach the wooden cabins that make up Magoroku Onsen (Tazawako Tazawa, Semboku 014-1204, Akita Prefecture). The rustic spa hides deep in the mountains; in summer they’re lush with green, in winter they are a wonderland of snow and plumes of steam. Inside the onsen is a rustic tub hewn out of rock into which bright-blue water flows. The outdoor baths are by the stream, with the sound of running water adding to the tranquillity of the location.
Tokyo isn’t known for its onsens but it is possible to experience the bliss of geothermal waters in the Japanese capital. Some of the city’s onsens are more like waterparks and others are combined with indulgent day spas – quite a pleasing combination. Maenohara Onsen Saya-no-yudokoro (3-41-1 Maenocho, Itabashi 174-0063, Tokyo Prefecture) is in the traditional style, located in an old house in the north of the city. Its water, a greeny-brown colour thanks to natural salts, comes from 1500 metres below Tokyo.
Nudity is a must
It’s true: the only suit generally allowed at an onsen is your birthday suit. In Japan, it’s no big deal – everyone is naked and no-one is going to stare at you. However, if you’re too self-conscious to strip off, try a ryokan that has a private rotenburo (an outdoor bath). Note that these rooms will be more expensive.
Keep it clean
Wash your body thoroughly before entering the onsen. Getting into the water while dirty – or full of soap suds – is a huge no-no.
If you think a little Dutch courage might help you get nude in front of strangers, think again. Drinking alcohol or being drunk while bathing is not acceptable.
Split up – briefly
Hot springs are often segregated so heterosexual couples can’t bathe together.
Cover your tattoo
Some onsen do not accept bathers with tattoos. This was initially to deny entry to members of Japanese organised-crime groups known as yakuza. If you’re inked, ensure the onsen is tattoo-friendly before entering – some will accept decorated types if the tattoos are covered with bandages.
You’ll generally be issued with a large towel and a small towel. Leave the larger one in the changing room with your clothing and take the smaller towel to the bath – but ensure it doesn’t enter the bath with you.
Keep your head above water
Don’t immerse your head in the water. If you have long hair, make sure it’s tied up.
The onsen isn’t for swimming or splashing around: it’s for soaking, contemplation and quiet conversation.
This article was originally published in 2016 and has been updated.