These are the Hot Springs that are attached to Mira's Tavern and Inn. These are free to people staying at the Inn and charge a small coin of 5 ryo for anyone else who comes to use it.

The springs are artificial, quite obviously, as they are on an airship, but like the training room, is a piece of heavenly outdoors somehow brought onto the airship. There's even a waterfall.

There is no separation for girl and boy baths.