What it looks like here is a combination bathroom/tanning room, perhaps? There’s definitely the shower (with a full glass exterior) and what looks like a bed to sit back and relax in. It’s fairly exposed for a shower, so it’s a wonder if guests would really want to use it.
Certainly, this is a separate room that can be locked for better privacy. Either way, it’s hard not to be enamored with it. There’s even a nice view to be had.