Ginzan Onsen — photo: さかおり · CC BY-SA 4.0 · Wikimedia Commons
Tohoku onsen: Ginzan, Nyuto, Sukayu, and the water
You have seen the photo: a narrow street of wooden inns, gas lamps, snow on every roof, a river down the middle. That is Ginzan, in Yamagata, and it is on every list of Tohoku onsen, along with Nyuto, Sukayu, Zao and a handful of others. The lists tell you which is prettiest. They do not tell you that these places are hours apart on different railway lines, that some of them are shut for five months of the year, or that the water in Tohoku includes some of the strongest in the country.
The hottest corner of Japan
Our database holds 1,538 onsen towns across Japan, and 266 of them are in the six prefectures of Tohoku: Aomori, Iwate, Akita, Miyagi, Yamagata and Fukushima. Fukushima alone has 67, the third-highest count of any prefecture after Hokkaido and Nagano.
For 175 of the Tohoku towns we have a source temperature on record, and 121 of those come out of the ground at 42 °C or above. That is 69 percent — a higher share than Hokkaido (96 of 146), and well above the national figure of 573 of 1,167, just under half. Forty-one Tohoku towns are recorded above 60 °C, and ten above 80 °C. Only 15 are below 25 °C and need heating.
The water is also unusually acidic. Only 26 towns in our whole database are recorded below pH 3, and 10 of them are in Tohoku. Of the 47 towns listed with an acidic spring, 16 are here. Tohoku also has 71 of the 311 sulfur towns. If you want water you can smell from the car park, this is where to look.
How the region is laid out
The Tohoku Shinkansen runs up the east side from Tokyo: about an hour and a half to Sendai, a little over two hours to Morioka, about three hours to Shin-Aomori. Two branch lines split off it: the Yamagata Shinkansen west from Fukushima to Yamagata, and the Akita Shinkansen west from Morioka to Akita. Almost every onsen worth the trip is a bus ride from one of these lines, not on them.
We measured the straight-line distance from each main station to every Tohoku onsen town we hold both coordinates and a temperature for. Within 50 km of Sendai Station there are 12, and only 6 reach 42 °C. Between 50 and 100 km there are 36, and 29 of them do. Fukushima Station does better: 30 towns within 50 km, 23 of them at 42 °C or above. So does Aomori: 26 within 50 km, 20 of them hot. The big city is not where the hot water is; the mountains an hour out are.
From Sendai: easy, but mostly gentle
Akiu is Sendai's own onsen town, about 50 minutes by bus from the station, with 16 inns in our records. It is a salt spring. Sakunami, about 25 km from the station on the Senzan Line, is a 50 °C salt and sulfate spring with river-side outdoor baths. Both are fine for a first night after landing at Sendai Airport, which has direct international flights.
For stronger water, go north to Naruko, about an hour and a half from Sendai by Shinkansen to Furukawa and then the local line. Our records list four water types in the Naruko area — salt, bicarbonate, sulfate and sulfur — and the neighbouring towns of Higashi-Naruko (14 inns) and Kawatabi (34 to 46 °C) are part of the same cluster. It is one of the few places in Japan where you can walk between baths of visibly different colours in an afternoon.
Yamagata: Ginzan and Zao
Ginzan is a former silver-mining town on a salt and sulfur source recorded at 44 to 65 °C. From Tokyo it is a little over three hours on the Yamagata Shinkansen to Ōishida, then about 40 minutes by bus. The town is small — one street, a dozen or so inns — and in recent winters the local authorities have limited day visitors in the evening, when the lamps come on. If you want to see it lit, stay the night, and check the current rules before you go.
Zao, about 40 minutes by bus from Yamagata Station, is a ski town with acidic, sulfurous water; our records list five water types there. It is the easiest strong-water town to reach in Tohoku, and the big outdoor bath by the river is a short walk up from the bus terminal.
Akita: Nyuto and the acid of Tamagawa
Nyuto is not one town but seven inns scattered through beech forest above Lake Tazawa, each with its own source. Between them our records list salt, bicarbonate, sulfate, sulfur and radon springs. The best known is Tsurunoyu, a thatched old inn whose milky outdoor bath is mixed. From Tokyo it is about three hours on the Akita Shinkansen to Tazawako Station, then about 50 minutes by bus. Overnight guests can buy a pass, the 湯めぐり帖 (yumeguri-chō), to bathe at all seven inns.
North of Lake Tazawa is the strongest water in the region. Tamagawa is a single large inn on a source recorded at 98 °C, pH 1.05, with a flow of about 9,000 litres a minute. That pH is about the same as Kusatsu (1.0), the town most people name as Japan's most acidic. The water stings any small cut, and the inn also offers diluted baths. It closes for the winter, roughly from December to April.
Nearby on the Hachimantai plateau, Goshogake is recorded at 85 °C and pH 1.8. Further south, near Yuzawa, Oyasukyō is recorded at 98 °C: steam jets out of the rock wall of the gorge, and you walk down to look at it.
Aomori: snow and a temple bath
Sukayu, about 70 minutes by bus from Aomori Station into the Hakkōda mountains, is one of the snowiest inhabited places in Japan. Its big wooden bath, the 千人風呂 (sennin-buro), "thousand-person bath", is mixed, with set women-only hours. Our records list five water types, including acidic and sulfur.
Asamushi, 63 °C, is on the coast about 20 minutes by train from Aomori, and is the place to go if you arrive late. At the far north of Honshu, Shimofuro is a sulfur town recorded at 65 to 95 °C with 10 inns, facing the strait towards Hokkaido.
Osorezan is a temple on the rim of a volcanic lake, with small bath huts inside the precinct fed by a 70 to 90 °C source at pH 1.9 to 2.7. The bathing comes with the temple entrance fee. The temple is open only from May to October.
Iwate and Fukushima: the ones with inns and trains
Tsunagi, about 30 minutes by bus from Morioka, is the opposite of Tamagawa: a sulfur spring at pH 8.7 to 9.5, with 15 inns and about 2,000 litres a minute. Alkaline water like this feels slippery on the skin — and on the floor. West of Hanamaki, Namari is a single old inn whose main bath is deep enough that you bathe standing up.
Fukushima is the closest part of Tohoku to Tokyo, about an hour and a half by Shinkansen. Iizaka is 25 minutes from Fukushima Station on a local train; Takayu, a milky sulfur town with 10 inns, is about 40 minutes up the mountain by bus. In Aizu, Higashiyama has 23 inns on a 45 to 58 °C source. And in the Bandai area, Nakanosawa is recorded at 68.3 °C, pH 2.1, and about 14,200 litres a minute: strongly acidic water, in large volume, with 11 inns.
Winter changes everything
Tohoku in January is exactly the snow-bath picture people come for, and it is also when parts of it stop working. Osorezan and Tamagawa close. The Hachimantai mountain road closes, and so does Sukawa, high on Mount Kurikoma (pH 2.3). Buses run less often, and the last one up to a mountain inn can leave mid-afternoon. On the Sea of Japan side it can snow for days at a time.
Plan to arrive before dark. If you are changing from the Shinkansen to a bus, check the bus times first and build the train around them, not the other way round.
Things not to do
Do not try to see Ginzan, Nyuto and Sukayu on one four-night trip. They are on three different lines, and you will spend the days on trains. Pick one or two: Yamagata and Miyagi pair well, and so do Akita and Aomori.
Do not let the water at Tamagawa, Goshogake, Zao, Sukayu or Osorezan near your eyes, and do not wash your face with it. Rinse with plain water after the bath if your skin feels tight.
Do not wear silver jewellery into any of the acidic or sulfur baths; it can blacken.
Do not drive a rental car up a mountain road in winter unless you have driven on snow and ice before.
Do not assume a mixed bath is an exception you can ignore. At Tsurunoyu and Sukayu it is the main bath. If you are not comfortable, use the separate indoor baths or the women-only hours.
New to this? Start with how an onsen stay actually works. For what the water types mean, see reading the water sign and sulfur onsen. Thinking about a snow bath? See when to go. For the rest of the country, see where Japan's hot springs actually are and Hokkaido onsen.