

About this spring
A hot spring resort at the entrance of Kurobe Gorge in Toyama Prefecture, famous for its deep forested canyon and the Kurobe Gorge Railway. The spring water here is shared with Kuronagi Onsen via a 7-kilometer pipeline, one of the more unusual infrastructure arrangements in Japan's onsen world.
Data: Wikipedia (CC BY-SA 4.0) · OpenStreetMap (ODbL)
Highlights
- Kurobe Gorge railway
- Selene Museum of Art
- 7-km shared pipeline
- Mountain canyon setting
Suitability
Mineral chemistry
Simple thermal springs (単純温泉) have a lower dissolved mineral content than other spring types but are valued for the pure therapeutic effect of heat immersion itself. The warmth increases core body temperature, promotes sweating, eases muscle tension, and improves peripheral circulation. Simple thermal springs are the most common onsen type in Japan and are recommended as the gentlest introduction to onsen bathing — suitable for a wide range of health conditions and ages.
Simple thermal springs are the most broadly accessible onsen type. Standard precautions apply: avoid bathing within 30 minutes of eating, keep soaks to 10–15 minutes for first-timers, and hydrate before and after.
History
Unazuki Onsen was established in 1923 during the Taisho period, founded alongside the development of the Kurobe hydroelectric project as workers required accommodation and rest facilities.
The resort attracted poets and writers who came for the mountain scenery. The Unazuki International Center later opened the Selene Museum of Art, showcasing works by Japanese artists inspired by the gorge landscape. The opening of Unazuki Onsen Ski Resort in 1956 expanded the town's appeal through winter months.
Local guide
From Toyama Station you take the Ainokaze Toyama Railway east along the coast until Uozu, then change to the Toyama Chiho Railway for Unazukionsen Station, the end of the line and the beginning of the Kurobe Gorge. The gorge starts right at the edge of town. You can stand at the riverbank and look straight into a narrow V-cut of dark rock where the Kurobe River runs fast and green below. The mountains rise almost vertically on both sides, and somewhere up in that slot is one of Japan's most challenging dam construction sites. Unazuki Onsen was built in 1923 precisely because of that dam project, sited here as a rest point for the workers who needed somewhere warm to stay.
The spring water was piped seven kilometers downstream from the Kuronagi Onsen source up in the gorge, a remarkable feat for 1923, and the same pipeline still supplies the town today. The water is a simple alkaline type, colorless and almost entirely odorless, with a pH of around 8.15. At source temperature it runs between 92 and 98 degrees Celsius, hotter than most springs in Japan, so every bathhouse blends it down before it reaches you. In the bath it feels smooth, softening on the skin without the heavy mineral density of more chemically complex springs. It is a clean, uncomplicated soak that suits the working-town character of the place.
The Kurobe Gorge Torokko Railway runs from Unazuki Station into the gorge on a narrow-gauge track originally built for dam construction. The open-sided carriages move slowly along cliff ledges above the turquoise river, through tunnels and over bridges, for twenty kilometers into the mountains. It is one of the few ways to experience the interior of a major Japanese gorge without serious hiking, and the combination of the train ride and the onsen on return makes Unazuki into a full day that earns itself completely.
The town has a pleasant low-key resort energy without being overdone. A footbath sits in the station plaza where you can soak while waiting for your train. The ryokan along the riverside offer outdoor baths with gorge views, and in autumn the maple and beech forest on the canyon walls turns the whole landscape orange and red above the blue water.
How this spring compares
Getting there
Take the Hokuriku Shinkansen to Toyama Station, then transfer to the Ainokaze Toyama Railway to Uozu, and then the Toyama Chiho Railway to Unazuki Onsen Station. The journey from Toyama takes about 1 hour and 20 minutes.
Amenities
Location & nearby
Unazuki Onsen, Kurobe, Toyama
Book a stay nearby
Hotels near Unazuki
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Data: OpenStreetMap (ODbL) · local tourism agencies
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