Wasezawa Onsen is a hot spring town in Fukushima, Japan. The water leaves the ground at 70.3°C, hot. It measures pH 7.8 — mildly alkaline, the slippery kind. Officially the water is classed as sulfate spring. Its sources put out around 535 litres a minute.
Clear water with a faintly bitter taste. Known for holding heat.
Figures from the town's Japanese Wikipedia article.
37.7258, 140.0663 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.