Located in the eastern part of Hokkaido, Akan-mashu National Park is one of the longest established parks in Hokkaido. Most of the park area is covered in natural forest comprising mainly subarctic mixed coniferous forest that is said to be some of the most primeval forests of all the national parks in Japan. The foundation for Akan-mashu National Park comprises three caldera landforms --the Akan Caldera, Kussharo Caldera, and Mashu Caldera --which were formed by the volcanic activity of the Chishima Volcanic Zone. With several volcano-lake pairs in close proximity within a narrow space, the area is nationally valuable.