open-air bath; outdoor hot spring
A bath, typically at a hot spring inn or public bath, located outdoors so bathers can enjoy the open air and scenery.
We could see the ocean from the inn's open-air bath.
Soaking in an outdoor hot spring while snow falls is the best.
As soon as I arrived at the inn, I soaked in the outdoor bath.
I booked a room with its own outdoor bath.
I gazed at the star-filled sky from the outdoor bath.