奥嬬恋温泉 is a hot spring town in Gunma, Japan. The water leaves the ground at 42.3°C, hot.
The water type for this town has not been identified yet. It is on the list to check.
Figures from the town's Japanese Wikipedia article.
36.5329, 138.5033 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.