Hokkaido Official Tourism Site HOKKAIDO LOVE!

A caldera lake formed by a volcanic eruption about 150,000 years ago. Four islands—Oshima, Kojima, Yaitai Island, and Churui Island—are scattered across the lake. Surrounded by the mountains of Mt. Meakan and Mt. Oakan, the southern shore of the lake is home to the naturally rich Lake Akan Hot Springs.

Lake Akan boasts a unique ecosystem, with the "Lake Akan Marimo," designated as a Special Natural Monument, being its most notable feature. These freshwater green algae form spherical shapes that are particularly distinctive.

You can visit the Marimo Exhibition and Observation Center on Churui Island via a sightseeing boat, or see them at the Lake Akan Eco-Museum Center in the hot spring town.

The seasonal landscapes are also part of Lake Akan's charm. The "Icebreaker Cruise," which navigates through cracks in the ice covering the lake, is a spring tradition that can only be experienced for one week in late April. In summer, you can enjoy activities such as canoeing and trekking to fully immerse yourself in nature. The "Lake Akan Marimo Festival," held annually from October 8th to 10th, features the "Thousand Torches" event, where prayer fires light up the hot spring town, creating a magical atmosphere. In winter, you can witness the breathtaking "Frost Flowers" that bloom on the frozen lake surface on cold mornings, and the mysterious "Ice Bubbles," where gas from the lake bottom is trapped in the ice. The thick ice on the lake allows for activities like smelt fishing and snowboarding. The popular event " Winter Fireworks," where fireworks are launched over the frozen lake, is held every February to March.