Sutdolbawi, located adjacent to Dongdo port of Dokdo, was where Dokdo volunteer guards sharpened their knives. The rock was named Sutdol (whetstone) as the characteristics of the rock were similar to that of a whetstone. Sutdolbawi stands 12.6 m high above sea level. It was formed after trachytic dike compositions intruded the fractures of the existing tuff breccia. Tuff breccia was eroded away and formed a sea-stack. In addition, the horizontal columnar-joints (formed when magma intruded the cracks of the rock and cooled) on the rocks create an unusual sight.