Akanuta Onsen Akanuta Tonneru no Yu

A wild sulfur spring (野湯, noyu) that seeps up along an old abandoned roadway near the Akanuta Tunnel, on the approach to Kamikochi in Nagano. There are no facilities whatsoever, steam vents through cracks in the old road surface and the sulfur smell hits you well before you arrive. Water temperatures vary widely by spot and season. This is very much a place for experienced wild-spring seekers; it is genuinely hazardous and not suitable for casual bathing.