Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Effortless float
LowHigh
Dense, salty water — you float without effort.
SodiumChloruresBrome
Tennen Onsen (Kamitoku no Yu), in Kochi, heats sodium-chloride water to 41°C. Bathers will find an indoor bath, an outdoor bath (rotenburo) and a sauna.
Insider tip — Tennen Onsen Kamitoku no Yu is a natural hot spring facility in Kochi Prefecture on Shikoku island, drawing clear saline geothermal water from coastal sedimentary layers. The warm sodium-chloride waters are prized for their ability to retain heat in the body long after bathing, making them ideal after Kochi's warm and humid summers. The onsen blends into the local community fabric, welcoming pilgrims walking the Shikoku 88-temple circuit. Kochi's mild climate makes outdoor rotenburo bathing pleasant year-round.