I know you can customize the bathtub to wood or marble and that will also come with a calming green water.
You can try looking for the lotus pond too, as that looks similar to the hot spring PWP. That might be a bit harder to get, though.
Gracie sells a bathrobe and a headband to go with it. You can find a bathroom shelf in Harvey's shop and you can go to the gardening shop to get some plants.
I know you can customize the bathtub to wood or marble and that will also come with a calming green water.
You can try looking for the lotus pond too, as that looks similar to the hot spring PWP. That might be a bit harder to get, though.
Gracie sells a bathrobe and a headband to go with it. You can find a bathroom shelf in Harvey's shop and you can go to the gardening shop to get some plants.
I'd use modern wood paneling on the walls for the more sauna type feel. The shower stall might also give a "spa" feel. Maybe the minimalist bed with the tea table next to it (and incense on the tea table) as a massage table?
Here's a bunch of pictures I found online that I used as inspiration for my spa/onsen (Japanese hot spring) room. I think if you wanted to make an outdoor hot spring room, the outdoor bath or lotus pond would be better than the bathtub, though.
not necessarily a sauna/hot spring room, bht this is my bathroom, probably the most room im proud of in the house! ii absolutely love it!!
*ii also used the 'whirlpool bath' and customized them to have flowers in them!! and yes it is all pinkish lol.. ii turned the light OFF, so its lit up using the wallpaper/flooring ii made, and all the lotus flower lamps on the floow, ii customized those to pink! and ii totally LOVE my glass 'doors' haha ii keep them closed and open when ii have company over lol
like someone said above, the incense would look good in there! i was planning on a hot spring in my house too, and was thinking about putting down some ores. like the crystal healing methods lol