Shirouma Yari Onsen Koya

One of the highest natural hot springs in Japan, at 2,100 meters in the Hakuba range. After a four-plus hour hike up, hikers step into a mixed open-air rotenburo (露天風呂) with sweeping alpine views, a sulfurous bicarbonate spring at 43 degrees flowing at 760 liters per minute, one of the highest-yield natural springs in Japan at altitude. The hut is rebuilt every year after winter dismantling; there's a women-only indoor bath for those who prefer it. Sunrise from the outdoor tub is a common reason people get up early.