Lake Shikotsu is a caldera lake south of Sapporo, among the clearest bodies of water in Japan and so deep that it never freezes, even in a Hokkaido midwinter. Which makes it a strange birthplace for an ice festival—and that is exactly the local logic. Beginning each December, workers spray the lake's water over wooden and metal frames, layer after layer, night after night, growing a village of ice objects on the shore of Shikotsuko Onsen. The name of the festival, hyoto, borrows the character for a great cresting wave and freezes it. By day the ice is blue—the deep mineral blue locals call Shikotsu Blue, the color of the lake carried up into the sculptures. By night the site becomes a lit labyrinth: tunnels of ice, towers of ice, a slide the children queue for in the dark, colors shifting through the frozen walls. On weekend evenings, fireworks burst over the lake. The festival began in 1979, invented by local people who wanted their unfreezable lake to have a winter face. Because the ice is grown, not carved, no two years look alike; temperature and wind decide the forms. Practically, this is the most accessible deep-winter festival in Hokkaido: about forty minutes by car or bus from New Chitose Airport, which makes it the first Hokkaido winter many travelers ever meet. The onsen baths of the lakeside inns are the reward for the cold. Lights come on at dusk. Dress heavier than you think necessary, and wear shoes that grip.