Gero Onsen — One of Japan's Three Great Hot Springs

Gero Onsen (下呂温泉) is ranked among Japan's 'Three Great Hot Springs' (alongside Kusatsu and Arima) for its exceptionally smooth, alkaline water (pH 9.2) that leaves skin silky after bathing. The spring water emerges at 84°C from underground volcanic fissures and flows into over 100 ryokan bath systems throughout the Hida River valley town. The water's high alkalinity strips dead skin cells, earning Gero the nickname 'beauty bath' (bijin-no-yu).

The town's layout is classic onsen-resort: a central hot spring street (Onsen-gai) lined with ryokan, souvenir shops, and public footbaths, with the Hida River running parallel. Three free public footbaths (ashiyu) allow day-visitors to sample the water, while the Gero Onsen Gassho Village combines open-air baths with relocated gassho-zukuri farmhouses. Multi-day ryokan stays with kaiseki meals and private baths are the traditional approach, but day-trippers can purchase tickets to rotational public baths (¥850) or specific ryokan day-use baths (¥1,000–2,000).