ハチ北温泉 is a hot spring town in Hyogo, Japan. The water leaves the ground at 31.5°C, cool enough that the baths here are usually reheated. It measures pH 8.4 — mildly alkaline, the slippery kind. Officially the water is classed as radioactive spring. Its sources put out around 220 litres a minute.
Contains trace radon that leaves the water quickly. Also called radium or radon springs.
Figures from the town's Japanese Wikipedia article.
35.4056, 134.5616 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.