![](https://www.oki-geopark.jp/wp/wp-content/uploads/2023/03/Tsutenkyo-Arch-Kuniga-Coast-900-1.jpg)
Geohistory - Rocks from Volcanic Islands Period
Geosites / Nishinoshima Town
This sea arch was shaped naturally by erosion from the rough waves of the Sea of Japan. It was once the entrance to a sea cave, but landslides caused the back of the cave to collapse and crumble away, leaving the shape we see today.