Tsuitoshi

"A six-minute walk from the Shirahone Onsen Tourist Information Center. This rock tunnel can be seen on the upper reaches of the river from the suspension bridge past Ryujin Falls. ""Yu"" means ""hot water"" or ""hot spring,"" and as the name of the Yu River implies, its waters contain an abundance of the same minerals found in the hot springs of Shirahone Onsen; this tunnel is presumed to have been carved out of the rock over countless years by the river's swift current. The limestone rock tunnel is six meters tall and 20 meters long. People are not allowed into the tunnel, but visitors can enjoy the stunning natural scenery of the tunnel and its surroundings from close by. Erosion control construction was conducted in 2018 due collapse and flood risks."