Idei Oketsu (potholes of Idei)

"Idei Oketsu" is located upstream of the Matsuda River in Sukumo City, on the border with Ehime Prefecture. A pothole is a hole in which pebbles, etc., enter a depression in the rock, and when the pebbles, etc. are rotated by the current of the river, the surroundings are scraped away to form a hole. About 200 potholes can be seen in the bed of about 200m in length and about 40m in width, and it is designated as a "Natural Monument of Kochi Prefecture" because it is rare to find such a large number of potholes.