Akan Mashu National Park (阿寒摩周国立公園, Akan Mashū Kokuritsu Kōen) is located in eastern Hokkaido. The park is well known for its three beautiful lakes: Lake Akan, Lake Mashu and Lake Kussharo. Lake Mashu is of particular fame. Although often covered by fog, its waters are some of the clearest in the world.
Akan Mashu National Park is composed of two separate parts. The smaller, western portion contains Lake Akan with the lakeside hot spring resort of Akankohan Onsen. The larger, eastern part contains Lake Mashu, Lake Kussharo, Iozan (Sulfur Mountain) and centrally located Kawayu Onsen.