noun
hidden hot spring; secluded hot spring; secret hot spring
Refers to a hot spring that is not widely known, often in a remote or hard-to-reach location, prized for its quiet atmosphere and natural setting.
山奥の秘湯に一泊した。
I stayed overnight at a secluded hot spring deep in the mountains.
地元の人しか知らない秘湯を探すのが趣味です。
My hobby is searching for hidden hot springs that only locals know about.