Ohketsu means a pothole formed by rolling stones driven by whirlpools in the river. Pebbles rolling all the time gradually make a hole in the bedrock of a river taking about ten thousand years. A little downstream from Shima Onsen hot springs, eight ohketsu potholes, large and small, are found on the bed of the Shima River. The picture shows one of the largest ohketsu potholes, two meters in diameter and one meter deep. It is estimated longer than ten thousand years to form this big round hole. It is prohibited now to get into the river water as a dam was built upstream though, the local children used to splash water in the ohketsu potholes a long time ago.
Licensed tour guide,travel consultant, Masahisa Takaki.