Back when the Japanese and Europeans were still getting to know each other, one big difference between the two was that Europeans were certain that baths were very bad for you. One a month was one too many. Meanwhile, the Japanese had perfected the art of the soak in natural hot springs. The country’s first resorts were all built around pools warmed by the Earth itself—tiny, safe versions of a volcano. Check out an onsen yourself: Wash off completely before getting in to the pool, and note that they probably won’t let you in if you have tattoos. The Arima Onsen is reachable by a ropeway tram from Mount Rokko.