菊川温泉 is a hot spring town in Yamaguchi, Japan. The water leaves the ground at 32.8°C, cool enough that the baths here are usually reheated. It measures pH 8.2 — mildly alkaline, the slippery kind. Officially the water is classed as chloride spring and bicarbonate spring.
Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
Smooth, slightly slippery water. Often nicknamed bihada-no-yu, the water for beautiful skin.
Figures from the town's Japanese Wikipedia article.
34.1304, 131.0349 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.