Mashû-ko 摩周湖

Lake Mashû / Mashû-See

Akan Mashû National Park / Hokkaidô

Lake Mashū is a caldera lake on inactive volcano Mashū. The lake is up to 211.4 m deep. In the middle is the 110 m long and 40 m wide island of Kamuishu. On the eastern shore is the volcanic cone Mashū-dake. Lake Mashū is famous for its clear water, which once allowed 40 m visibility. The lake owes its very clear water to the fact that it is fed exclusively by melt and rain water and supports almost no flora and fauna. Lake Mashū does not have an outlet. The Kamuy-to (literally “Lake of the Gods”) is sacred to the Ainu. Even today, Ainu hold an annual celebration at the lake on a summer night.