Lake Mashu (Hokkaido): One of the World’s Clearest Caldera Lakes — Best Viewpoints & Misty Legend (2026)
Lake Mashu in winter. The small island at center is Kamuishu — the petrified grandmother of Ainu legend — with Mt. Kamuinupuri (Mashu-dake) rising on the right (Photo: Suicasmo / Wikimedia Commons, CC BY-SA 4.0) In 1931, scientists measured the water clarity of Lake Mashu (摩周湖, Mashū-ko) at 41.6 meters — at the time the […]