A caldera lake in Akan Mashu National Park, it is one of Hokkaido's leading tourist destinations. The view of Mount Oakan towering over the eastern shore is majestic, and it shows beautiful expressions in every season. There are four islands, and it is also famous for the spherical "Lake Akan Marimo", a special natural monument that is rare even worldwide. A hot spring town spreads out on the southern shore, and is bustling with tourists and anglers.