Shibu Onsen — photo: 663highland · CC BY 2.5 · Wikimedia Commons
Japanese Alps onsen: Nagano, Gifu, Toyama and the water
The Japanese Alps look compact on a map: one block of mountains in the middle of Honshu, with Nagano on the east side, Gifu on the west and Toyama to the north. Most lists of onsen there pick a dozen pretty towns from all three and put them side by side. What they skip is that the ranges in between are among the hardest in Japan to cross, that a town on the Gifu side can be four hours from one on the Nagano side, and that the hot water is not spread evenly at all.
Three prefectures, three very different pictures
Our database holds 1,538 onsen towns across Japan. Nagano has 101 of them, the second-highest count of any prefecture after Hokkaido. (The prefecture's own tourism board counts more than 200 hot spring areas; we list a place only when it has its own entry in Wikipedia or Wikidata, so small single-inn sources are often folded into a larger town.) Gifu has 55 and Toyama 48.
For 73 of the Nagano towns we have a source temperature on record, and 42 of them come out of the ground at 42 °C or above — 58 percent, against 573 of 1,167 for Japan as a whole, just under half. Eighteen are above 60 °C and six above 80 °C. Toyama does about as well: 26 of 42.
Gifu is the surprise. It has 40 towns with a temperature on record, and only 6 reach 42 °C. Fifteen are below 25 °C and have to be heated. Much of southern Gifu sits on granite, and its typical spring is cool, clear radon water: Gifu has 11 of the 108 radon towns in our database, second only to Yamaguchi. Almost all of Gifu's hot water is in two places, Gero and the Okuhida valleys under the northern peaks. If you are picking a Gifu onsen, those two are what the photos show.
Which base is closest to hot water
We measured the straight-line distance from five stations to every onsen town we hold both coordinates and a temperature for. Within 50 km of Nagano Station there are 53, and 38 of them reach 42 °C: the best ratio of any big station we have measured. Within 50 km of Toyama Station there are 41, with 25 hot. Matsumoto has 22 within 50 km, 11 of them hot; Takayama has 16, with 9.
Nagoya is where many visitors to this area land, and it is the weakest. Within 100 km of Nagoya Station there are 37 towns with a temperature on record, and only 5 reach 42 °C. Gero is one of them; the other four are bathhouses on the coastal plain. From Nagoya, Gero is the realistic hot-water night, and Okuhida is a second day further on.
Nagano: the snow monkeys and the towns around them
The 湯田中渋温泉郷 (Yudanaka-Shibu onsen-kyō) is a cluster of about nine small towns in one valley, about 45 minutes from Nagano Station on the private Nagano Electric Railway to Yudanaka. This is the hottest corner of the prefecture in our records: Kakuma is recorded at 98 °C, Andai and Honami at 97 °C, and Kanbayashi at 68 °C.
Shibu, with 35 inns in our records, is the one with the cobbled lane and wooden buildings. It has nine small public baths, the 外湯 (soto-yu), which are locked; if you stay the night in Shibu, the inn lends you the key. Day visitors are limited to one or two of them.
The snow monkeys are at Jigokudani, a single inn at the end of a 30-minute forest path from the Kanbayashi side, on a salt, sulfate and sulfur source recorded at 62 to 76 °C. The monkey park's pool is for the monkeys. You watch; you do not bathe with them. The inn has its own baths, which the monkeys sometimes visit. The monkeys come to the water most in the coldest months, roughly December to March, and the path is packed snow then: wear shoes with grip.
Nozawa, about 25 minutes by bus from Iiyama Station on the Hokuriku Shinkansen, is a ski town on a sulfur source recorded at 42 to 90 °C. It has thirteen free public baths run by the villagers, and the water in some of them is very hot. In the northwest of the prefecture, Hakuba-Happo is recorded at pH 11.5, the highest pH of any town in our database; water like that feels slippery on the skin and makes floors slippery too.
Nagano: Matsumoto, Shirahone and Kamikochi
Asama (42 to 52 °C) and Utsukushigahara (45 °C, about 1,250 litres a minute) are both on Matsumoto's edge, 20 minutes by bus from the station: easy for a night after the castle. Shirahone, deep in the mountains west of Matsumoto, is the famous milky one, a bicarbonate and sulfur source with 12 inns in our records. It is about two hours from Matsumoto by train and bus, and the bus runs less often in winter.
Kamikochi has two inns with sulfur baths in a valley where private cars are banned all year. The road in closes completely from mid-November to late April. On the other side of the Azumino plain, Nakabusa sits at the trailhead for the Northern Alps, on a sulfur source recorded at 56 to 97 °C, about 770 litres a minute.
Gifu: Gero and Okuhida
Gero is about an hour and 40 minutes from Nagoya on the Limited Express Hida. Its source is recorded at 84 °C and pH 9.0: a simple spring, clear and slippery. It is a real town with a station, many large inns and a riverside, and the easiest hot-water stop between Nagoya and Takayama.
Okuhida is five small towns up the valleys east of Takayama. Hirayu, about an hour by bus from Takayama, is recorded at 90 °C and about 13,000 litres a minute, with 26 inns. Shin-Hotaka, 52 inns, is at the end of the road beneath the Shin-Hotaka Ropeway, and our records list salt, bicarbonate and sulfur water there. Several Okuhida inns have large riverside outdoor baths, and some of them are mixed; check before you book if that matters to you.
Hirayu is also where the Gifu and Nagano sides meet: a bus runs from Matsumoto through the tunnel under the ridge in about an hour and a half. If you want Matsumoto and Takayama on one trip, Hirayu is the natural night in between.
Toyama: the gorge and the highest inn
Unazuki, at the mouth of the Kurobe Gorge, is recorded at 98.3 °C, pH 8.19, with 15 inns. The water is piped down from a source further up the gorge. The small open trains of the Kurobe Gorge Railway run up from here past Kuronagi (also 98.3 °C), Kanetsuri and Meiken (98 °C). They run only from spring to late autumn, and parts of the line have been closed after damage in recent years, so check which section is running before you plan around it.
Mikurigaike is an inn at about 2,400 m on the Tateyama Kurobe Alpine Route, often called the highest onsen inn in Japan. Its water is recorded at 70 °C and pH 3.1, an acidic sulfur spring. The route is open only from mid-April to late November. Takamagahara, 51 °C, is further in still: there is no road, and reaching it takes a long day or two on foot.
Things not to do
Do not plan Nozawa, Shirahone and Okuhida as a loop without checking a map in winter. The direct mountain roads between the Nagano and Gifu sides are closed for months, and the detour can add hours.
Do not step into the monkeys' pool at Jigokudani, touch or feed the monkeys, or carry food in the open on the path.
Do not assume a public bath in Nozawa or Shibu is cooled for you. The water in the 外湯 can be close to 50 °C near the inlet. Test it with your hand, and if a local is in the bath, ask before you turn on the cold tap.
Do not wear silver jewellery into the sulfur water at Shirahone, Nozawa, Nakabusa or Mikurigaike; it can blacken.
Do not expect the dramatic outdoor baths in the photos near Nagoya. If the water matters to you, go to Gero or further.
New to this? Start with how an onsen stay actually works. For the water, see reading the water sign and sulfur onsen. For public-bath manners, see onsen etiquette. For the rest of the country, see where Japan's hot springs actually are, onsen from Tokyo and Tohoku onsen.