Running along the deepest valley in Japan, the open-air Kurobe Gorge Railway takes you on a 90-minute ride past gushing springs and waterfalls. You might even see wild monkeys or a serow, a type of mountain goat. One of the best views is from the 128-foot-high bridge called Atobiki-kyo. Bring a windbreaker, even in summer, as it's a cold and damp ride. Kuronagi Onsen, Kanetsuri Onsen, and Meiken Onsen are three of the hot springs along the trolley route. You can get off at any of them and enjoy a soak.