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オホーツクオムイ温泉 is a hot spring town in Hokkaido, Japan. The water leaves the ground at 66°C, hot. It measures pH 7.6 — mildly alkaline, the slippery kind. Officially the water is classed as chloride spring. 1 inns take visitors here.
Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
Figures from the town's Japanese Wikipedia article.
44.5267, 143.0574 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.