Lake Shikotsu is a caldera lake formed by a volcanic eruption about 44,000 years ago, located in Shikotsu-Toya National Park. One of the clearest lakes in Japan. On this winter scuba diving tour, licensed divers can explore Lake Shikotsu’s crystal-blue waters at their most transparent and serene. Due to its resistance to Hokkaido’s extreme cold, Shikotsu is known as “Japan’s northernmost unfrozen lake.” Even when a section does freeze, it’s thin enough to cut a hole and go scuba diving. Your drysuit will keep you warm as you swim, so you can comfortably enjoy the amazing spectacle of light reflecting from the ice above you.