Akan Mashu National Park

Akan Mashu National Park protects a volcanic caldera landscape in eastern Hokkaido, Japan, designated on December 4, 1934 as one of the country's first national parks. The park covers roughly 905 square kilometers split between the Akan and Kawayu districts, taking in the Akan Caldera, Mount Meakan and Mount Io. Its centerpiece is Lake Mashu, among the clearest lakes in the world with visibility to about 40 meters, alongside Lake Kussharo and natural hot springs. The park is also one of the few places in Japan where marimo, ball-shaped colonies of algae, grow to notable size in the wild.