I cannot recommend this amazing spot enough! Note that the hot springs are only available to resort guests.
The grounds of this location are absolutely incredible – food is amazing, and the hot springs are magical. Each hot spring boasts its own naturally occurring hybrid mix of minerals, which vary from place to place depending on the geology of the area.
For the storied history of this location and the hot springs, read more here.
Note that you do have to make a decent trek on a pretty road, so make sure you have a car that can handle some dips. Link to directions here.