Shima Pothole Group

Overview

The Shima Pothole Group is a cluster of potholes located in Shima, Nakanojo-machi, Agatsuma-gun, Gunma Prefecture, formed in the Shima River. Potholes are circular holes created when swirling river currents cause stones and sand to repeatedly grind against the riverbed, eroding the rock. The Shima Pothole Group is a breathtaking testament to the sculpting power of nature over tens of thousands of years. There are eight potholes of varying sizes; the largest measures 2.9 meters in diameter and 1.5 meters in depth. A dam was once planned for the Shima River, but local residents successfully opposed the project. Had the dam been built, these remarkable potholes would likely have been submerged. Today, the Shima Pothole Group is protected as a designated natural monument of Gunma Prefecture. Visitors can descend a staircase to reach the riverbank for an up-close view of these impressive potholes. The sheer scale of these natural formations is truly awe-inspiring. The area surrounding the potholes offers a refreshing stroll along the clear waters of the Shima River, amidst lush greenery. Don't miss this remarkable sight during your visit to Shima Onsen.