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🇯🇵 Japan · Minakami, Gunma Prefecture
♨ Temperature
42°C
⛰ Altitude
680 m
⚗ pH
7.2
💧 TDS
820 mg/L
🌊 Flow rate
55 L/s
📅 Established
Inn established 1936; spring in use since Edo period
✓ Verified on 2026-07-22
Takaragawa Onsen is among the most celebrated outdoor onsen experiences in Japan, and by some measures the most dramatically scaled: four large outdoor communal baths (rotemburo) built directly on the banks and within the shallows of the Takara River, in a deep forested gorge in the Minakami area of Gunma Prefecture. The largest bath can accommodate hundreds of bathers simultaneously while feeling intimate, positioned between mossy boulders at the river's edge with the sound of the current and the forest canopy overhead. The water — slightly alkaline, mildly sulphurous, crystal clear — emerges from the earth at 42°C and flows into open-air pools that are used year-round. In winter, the steam above the pools meets cold mountain air to create a dramatic mist effect while snowfall settles on the surrounding cedar and beech forest. The approach to Takaragawa involves a narrow mountain road through the Akiyama gorge area, and the journey itself is part of the experience: Gunma's mountain interior is one of the most intact traditional rural landscapes in the Kanto hinterland. The Oku-Takaragawa Onsen Osenkaku inn maintains the baths and offers traditional kaiseki ryokan accommodation.
| Sulphur (H₂S) | 1.2 mg/L |
| Bicarbonate | 340 mg/L |
| Sodium | 128 mg/L |
| Calcium | 58 mg/L |
| Silica | 48 mg/L |
| Magnesium | 14 mg/L |
Minakami in Gunma Prefecture sits within the Jōshinetsu Kogen (Joshin-Etsu Highlands) region, an area of volcanic and geothermal activity associated with the Niigata-Kobe Tectonic Zone. The Tone River, Japan's second-largest river by drainage area, originates near Minakami and its watershed was historically the primary water supply for Edo (Tokyo). The mountain landscape of upper Gunma has been accessible by rail since the Meiji era, making it one of the earliest developed recreational onsen regions for urban Japanese.
Takaragawa gained international attention when it appeared in travel writing as 'the onsen that allows mixed bathing' — one of the few major Japanese hot springs maintaining the konyoku (mixed-gender outdoor bathing) tradition. This practice, once universal in Japan, was largely suppressed during the Meiji-era Westernization of Japanese public morality. Takaragawa's scale makes it possible for couples and families to bathe together outdoors, which is considered a distinctive feature by both Japanese and international visitors.
The spring flows at 55 L/s entirely by natural artesian pressure from the mountain bedrock, requiring no pumping. The Takara River gorge is protected as part of the Jōshinetsu Kogen National Park, and the surrounding old-growth beech and cedar forest is managed under national park conservation standards.
Phone+81 278-75-2611
Websitewww.takaragawa.com
Address1899 Fujiwara, Minakami-machi, Tone-gun, Gunma 379-1728, Japan