湯浦温泉 is a hot spring town in Kumamoto, Japan. The water leaves the ground at 42°C, hot. It measures pH 8.43 — mildly alkaline, the slippery kind. Officially the water is classed as simple spring. 1 inns take visitors here.
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.
32.2749, 130.4994 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.