鷲倉温泉 is a hot spring town in Fukushima, Japan. The water leaves the ground at 60.2–69°C, hot. It measures pH 2.7–6.5 — acidic. Officially the water is classed as sulfate spring, iron spring, acidic spring and sulfur spring. Its sources put out around 100 litres a minute. 1 inns take visitors here with room for about 135 guests.
Clear water with a faintly bitter taste. Known for holding heat.
Turns reddish brown as the iron meets air. The water is clear at the source.
Strongly acidic, sometimes below pH 2. It stings on cuts and is not for long soaks.
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.
37.6686, 140.2606 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.