Nachikatsuura Onsen

The JR Kuroshio limited express from Osaka takes just under four hours to reach Kii-Katsuura Station, and for most of that journey you are following the coast of the Kii Peninsula as it gets progressively wilder. The cliffs get taller, the bays get deeper, and the forest behind the shoreline thickens into the kind of dark, wet, cedar-and-camphor growth that has covered these mountains for a thousand years of pilgrimage. When you step off the train at Kii-Katsuura, the air is warm, heavy with salt, and faintly sweet with something you cannot quite name. The harbor is immediately below the station, and on a clear day you can see a few small rocky islands sitting low in the deep blue water just offshore.

The hot spring water in the Nachikatsuura area runs sodium chloride, clear and neutral at pH 7.6, and it flows in several places along this small coastal town. The water is warm and fairly dense on the skin, with the kind of slight salinity that makes your body feel faintly supported in the bath rather than just submerged. Temperatures range widely across the different facilities, from a gentle 38 degrees to nearly 62 at the hottest source, so it is worth asking before you commit. The ocean is the real context for the bathing here. Some of the most sought-after baths are literally inside the rocky peninsula, carved into sea caves where waves push through gaps in the stone floor and the Pacific light filters in sideways in the morning.

Hotel Urashima's Bokido bath is the most famous of these cave baths, its name translating roughly as the cave where one forgets to return home. You approach it by crossing to the hotel's peninsula by boat from the harbor, a five-minute crossing that already puts you in a different frame of mind. The cave is naturally formed, high-ceilinged, and open at the ocean-facing side, so you are bathing while waves break below you and seabirds pass at eye level. It does not feel like a hotel amenity. It feels like something the sea hollowed out and the town was wise enough to leave mostly alone.

Above the town, forty minutes by bus, Nachi Falls drops 133 meters in a single unbroken plunge, the longest single-fall waterfall in Japan, and it has been drawing people here for purification and prayer for over 1,300 years. The Kumano Nachi Taisha shrine sits at its base, one of the three grand shrines of the Kumano Kodo pilgrimage route. Coming down from the falls and back to the harbor, then crossing to the cave bath as the afternoon light changes on the water, is a genuinely full day in a place that has been managing the business of cleansing people, spiritually and literally, for a very long time.