The peak of Rausu-dake (羅臼岳), the tallest mountain in Shiretoko at 1661m, can be reached in around four-and-a-half hours from the Iwaobetsu Youth Hostel, passing a natural rotemburo on the way. From the summit there are spectacular views along the whole peninsula, and to the east you should be able to see Kunashiri-tō, one of the disputed Kuril Islands, or “Northern Territories” as they are known in Japan. It takes a full day to continue across Rausu-dake to Rausu.
Iō-zan (硫黄山), the active volcano that produces hot water for the Kamuiwakka-no-taki waterfalls, is a more difficult climb. The trail begins beside the Shiretoko Ōhashi, the bridge just beyond the entrance to the falls. A hike to the 1562m summit and back takes at least eight hours and can be combined with a visit to the hot waterfall.
You’ll need to be a serious mountaineer to tackle the difficult ridge trail linking Iō-zan and Rausu-dake; bring a topographical map, take precautions against bears and plan to stay one or two nights at the campsites along the way. The Rusa Field House (ルサフィールドハウス), about 10km north along the coast from Rausu, can provide rules and current information to mountaineers and sea kayakers.