Lake Mashu

Lake Mashu is a caldera lake in Teshikaga Town, Kawakami District, Hokkaido, famous for having Japan’s second-highest water transparency. On clear days, its deep blue color is often called "Mashu Blue." Lake Mashu is also recognized as a Hokkaido Heritage site. In Ainu, the lake is called "Kamuito" meaning "Lake of the Gods," and in recent years it has become popular among younger visitors as a power spot. Because it has no river inflow or outflow connection, it is considered a particularly pure lake with little outside material entering it. The lake is also known for frequent fog—roughly three months of the year it is covered—creating an atmospheric, mysterious scene on foggy days. There is even a saying that couples who see the foggy Lake Mashu will get married. It is popular with both domestic and international visitors, attracting over one million people annually. From Mashu First Observatory, you can take in a panoramic view of the lake’s blue waters and the small island Kamui-shu in the center. Access is by bus from Mashu Station (about 20 minutes). Nearby attractions include Kaminoko Pond, Mt. Io (Sulfur Mountain), and Kawayu Onsen, making it a good area to tour together.