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🇯🇵 Japan · Aomori
♨ Temperature
42°C
⛰ Altitude
925 m
⚗ pH
2.5
💧 TDS
1400 mg/L
🌊 Flow rate
25 L/s
📅 Established
1684
✓ Verified on 2026-07-22
Sukayu Onsen holds a special place in Japanese hot spring culture as both one of the oldest continuously operating onsen in the Tōhoku region and the location of the largest traditional wooden communal bath in Japan. The Hiba Senninburo — literally the 'bath of a thousand people' — is a vast timber-vaulted space where up to 160 bathers can soak simultaneously in large wooden tubs fed by strongly acidic, milky white sulphurous water. The onsen sits at nearly 1,000 metres in the volcanic Hakkōda Mountains, surrounded by beech forest that transforms into a winter snow landscape famous throughout Japan. The water, designated an officially registered National Hot Spring Cure Resort, has a pH of around 2.5 — among the most acidic natural springs in the country.
| Sulphur | 85 mg/L |
| Aluminium | 22 mg/L |
| Iron | 18 mg/L |
| Hydrogen | 12 mg/L |
Sukayu's founding tradition traces to 1684, when it was established as a waystation and healing spring in the mountain forests of Aomori. The Hiba Senninburo wooden bathing hall has been maintained in its traditional form for over a century and is considered one of Japan's great architectural bath spaces.
Sukayu is one of a small number of onsen in Japan that still operates a traditional konyoku (mixed bathing) area in its historic communal hall — a practice now rare in modern Japan. The combination of the acidic white water, the vast wooden ceiling, and the mountain isolation creates an onsen experience of exceptional cultural depth.
The surrounding Hakkōda Mountains are protected as a national forest reserve. Sukayu manages visitor flow carefully to preserve the character of the communal bath space and the springs' natural flow rate.
Websitewww.sukayu.jp
AddressSarukura-86, Aomori-shi, Aomori 030-0111, Japan