It's called a "chan".
We found this place in a special hide away up on the neighboring mountain.
It's kind of a mix between steam room/hot tub.
And there's always a cold pool for you to dunk into nearby.
It's also not for the weak of heart (literally, people who have weak hearts or experience high blood pressure, this is not for you).
But I loved it!
Definitely don't need more than 1-2 hours if you're with a group of friends and this your first time in one of these.
We walked back and made it RIGHT before a huge rain storm!
And spent the evening relaxing and listening to the crickets singing through the foggy wood.