Kamuiwakka Falls is a series of warm waterfalls on the Kamuiwakka River, heated by volcanic activity from Mount Iō above. The water emerges from the mountain already warm and slightly acidic, and you can wade up through the lower falls — pool after pool of warm water in a forest gorge — until you reach the main falls and their natural tub of heated water. The experience is extraordinary: a natural hot spring you hike into rather than just sit beside.
Access has been modified over the years as the popularity grew and safety concerns emerged. Currently, only the first falls area is open to the general public; the upper pools require a guide. The road to Kamuiwakka beyond Shiretoko Goko is closed to private cars during peak season (July–October), with shuttle buses running from the Utoro area. Bring waterproof sandals for wading — the rocks are slippery.