noun
natural hot spring
Refers to a hot spring whose water is naturally heated by geothermal activity, as opposed to an artificially heated bath. Often used in travel and onsen facility descriptions.
この旅館は天然温泉を引いています。
This inn draws water from a natural hot spring.
天然温泉の成分が肌に
The minerals in natural hot spring water are said to be good for the skin.