Run by local adventure guide Watanabe Toshiya, Rera Mosir is the best place on the island for active types – whether you're here to climb Rishiri-zan in summer or ski the backcountry in winter. (It's also one of the few places open year-round.) Though small, it's modern and run like a hotel, and even has an onsen bath.
It does free shuttle runs to/from the port and the trailhead for Rishiri-zan; if you want to explore on your own, its rental cars are the cheapest on the island. The seafood dinners are good, too. Prices drop by ¥2000 to ¥2500 in the winter.