Atosanupuri, the Ainu name for Mount Io, is an active volcano that sporadically erupts into clouds of sulfur. To explore this fascinating landmark, walk along a 2.4-kilometer trail that connects the mountain to the Kawayu Onsen. Despite the relatively short distance and low elevation, you can admire beautiful alpine plants and trees that can normally only be seen on steep mountain paths thanks to the effects of Mount Io’s volcanic activity on the soil. Why not enrich your adventure with the help of a guide? A local expert can show you how past eruptions have carved out this stunning landscape and created the perfect habitat for unique wildlife.