Lake Akan — Marimo Moss Balls & Ainu Culture

Lake Akan (阿寒湖) is a volcanic caldera lake famous for marimo (毬藻) — rare spherical algae colonies that grow naturally only in a few locations worldwide. The largest marimo reach 30cm diameter and live 200+ years, growing 5mm per year. The algae colonies are designated a Special Natural Monument and protected — viewing is possible at the Marimo Exhibition Center on Churui Island in the lake.

The lake shore is home to Ainu Kotan (アイヌコタン), Hokkaido's largest Ainu cultural village, where the indigenous Ainu people maintain traditional crafts, dance performances, and wood-carving workshops. The Ainu culture, language, and spiritual traditions (which view nature as sacred) were suppressed for centuries but are now experiencing revitalization. The village offers a rare window into Japan's indigenous heritage.