Hispersal Swamp, located in the west of Hamanaka Town, is a brackish lake where seawater flows in with the ebb and flow of the tide. Because of this, oysters, clams, sea urchins, and other fish are actively cultivated in Hissarubunuma. In winter, swans and red-crowned cranes fly to the lake, which is also used as a stopover for migratory birds.