大洗温泉 is a hot spring town in Ibaraki, Japan. The water leaves the ground at 15°C, cool enough that the baths here are usually reheated. It measures pH 7.7 — mildly alkaline, the slippery kind. Officially the water is classed as chloride spring. 7 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.
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