Loaded with major ions — the essential minerals (Ca, Mg).
Buoyancy
Effortless float
LowHigh
Dense, salty water — you float without effort.
SodiumChloruresBrome
Izumozaki Onsen occupies a historic coastal town in Niigata Prefecture once known as Japan's first oil-producing region, where petroleum was skimmed from seeps centuries before modern drilling began. The chloride-rich spring water emerges warm and warming, highly regarded for improving circulation and maintaining body heat during the long, cold winters of this Sea of Japan coastline. The town's literary heritage, as birthplace of the poet Ryokan, lends a contemplative atmosphere to the experience of bathing in these mineral-rich waters.
Insider tip — Izumozaki sits on Niigata's coastal plain where ancient sea deposits enrich the groundwater with sodium chloride, giving the bath a soft, skin-warming quality. The surrounding Sea of Japan coastline is dotted with fishing villages and rice paddies, making this a quietly authentic local onsen. Best visited on weekday mornings when regulars from nearby fishing households share the communal tub. The salted water retains heat exceptionally well, so brief dips of 10 minutes are advised.