Hokkaido Official Tourism Site HOKKAIDO LOVE!

This caldera lake was created by an eruption about 150,000 years ago. The lake is dotted with four islands: Oshima, Kojima, Yaitaijima, and Churuijima. Surrounded by the mountains of Mt. Oakan and Mt. Meakan, the lake is rich in nature with Lake Akan Onsen hot springs bubbling up along the southern shore of the lake.

Lake Akan has its own unique ecosystem, represented by the marimo, which has been designated a special natural treasure. A type of freshwater green algae, it is characterized by its round, spherical shape. It is rare in the world to find a colony of marimo larger than 15 cm in diameter, and there are only two places in the world, including Lake Akan, where marimo grow in clusters. Marimo can be seen at the Marimo Exhibition and Observation Center on Churuijima, which can be reached by a sightseeing boat ride, and at the Lake Akan Eco-Museum Center in the hot spring resort area.

Another attraction is that the scenery changes dramatically from season to season. The "icebreaking cruise," which takes visitors on a sightseeing boat while breaking the ice that covers the lake's surface, is a tradition that heralds the arrival of spring to Lake Akan, and can be experienced only for one week in late April. In summer, enjoy the great outdoors with activities such as canoeing and trekking. During the fall foliage season, "Senbon Taimatsu," a festival to thank the fire gods of the Ainu tribe and the earth, is held, creating a fantastic atmosphere with prayer fires lit in the hot spring resort area. In winter, visitors can enjoy the spectacular view of "frost flowers," which bloom on the frozen lake only on cold mornings, as well as wakasagi (smelt) fishing and snowboarding on the lake covered with thick ice. The popular "Fuyuhanabi" event, in which fireworks are set off over the icy lake, is held every year from February to March.