Kiyotsu Gorge just outside Tokamachi is one of the three top gorges in Japan. (The others are Kurobe Gorge in Toyama, and Osugi Gorge in Mie.) It is a really impressive sight, and a lovely little side trip if you find yourself on R353 between Tokamachi and Ishiuchi.
There used to be a walking path along the side of the gorge but falling rocks were a danger so in 1996 a tunnel along the side was completed. The tunnel is 750 meters long and leads to 4 viewing areas. Along the way are displays about the four seasons in the gorge, the plant and animal life, and information about the formation of the impressive rock cliff.
A couple of stuffed bears adorn the autumn display, and there is also an area with a video providing information about the gorge.
The gorge itself is stunning, with perpendicular rock walls formed by cooling lava into formations called columnar joints.
The walk up the tunnel to all the viewing points can take up to an hour and is a round trip of 1500 metres but it is well worth seeing each one as the all give different views of the beautiful nature all around the rock walls. (Please note that there are not bathroom facilities once in the tunnel.)
It is a great trip and well worth the 600 yen entrance fee for adults, 300 yen for children.