
Photo: Soren Bradley · CC BY 4.0 · Wikimedia Commons
沼尻温泉 is a hot spring town in Fukushima, Japan. The water leaves the ground at 71.8°C, hot. It measures pH 1.9 — strongly acidic, the kind that stings on a cut. Officially the water is classed as sulfur spring. Its sources put out around 10,000 litres a minute. 2 inns take visitors here.
The classic rotten-egg smell and milky white water. It can tarnish silver jewellery, so take it off.
Figures from the town's Japanese Wikipedia article.
37.6184, 140.2276 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.