The Saru River, 104 km long and the longest river in Hidaka, originates in the Hidaka Mountains and is a beautiful river that flows slowly through the four seasons. The river is also the source of numerous Ainu legends, such as "Kamui Yukara," which conveys the feelings toward the river that has nurtured the Ainu people's lives. The Saru River, the symbol of Hiratori Town, has an abundance of water, and plans are underway to effectively utilize the river, including the development of a dam. The lower reaches of the river are also known as a mecca for fishing for redfish.