Photo by Asturio Cantabrio, via Wikimedia Commons (CC BY-SA 4.0)
🇯🇵 Japan · Gifu
♨ Temperature
80°C
⛰ Altitude
220 m
⚗ pH
8.5
💧 TDS
390 mg/L
🌊 Flow rate
28 L/s
📅 Established
1265
✓ Verified on 2026-07-22
Gero Onsen has been counted among Japan's three finest hot springs since the Edo period, alongside Kusatsu and Arima. The town sits in a narrow river valley in Gifu Prefecture where the Hida River runs between steep forested slopes. The water is notably alkaline — pH 8.5 — and low in dissolved solids relative to its temperature. The town is small enough to walk across in minutes, with free public foot baths along the river promenade. Gero is also a gateway to the Hida Highlands and the historic village of Shirakawa-go.
| Sodium Bicarbonate | 260 mg/L |
| Silica | 72 mg/L |
| Calcium | 38 mg/L |
| Magnesium | 22 mg/L |
Gero's springs are documented in a poem by the Buddhist monk Fujiwara no Saneyori written in 1265, which first established Gero as one of Japan's premier onsen. The town's ryokan culture developed during the Edo period.
Gero is associated with the legendary folk hero Minamoto no Yoshinaka, who is said to have bathed in the springs after battle. The town celebrates this heritage each May with the Gero Onsen Festival.
Gero participates in Japan's national spring water protection framework, which regulates new borehole drilling and monitors aquifer pressure. The tourism association actively promotes off-peak travel to reduce seasonal concentration.