Photo: 投稿者 · CC BY-SA 3.0 · Wikimedia Commons
Wakoto Onsen is a hot spring town in Hokkaido, Japan. The water leaves the ground at 52.5°C, hot. Officially the water is classed as simple spring.
Mild and low in dissolved minerals. Usually clear and gentle on the skin, which is why these baths are often recommended for first-timers.
Figures from the town's Japanese Wikipedia article.
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.