Zero-threshold showers are very common in Mexico, and they open up a tiny space. The lack of doors or dividers demands that the floor be angled toward the drain, but also lends a roomier feeling. Check out that flip-up wooden seat against the wall — perfect for shaving.
Mirrors are the oldest trick in the book for making a small space feel bigger. Since you need them in the bathroom anyway, why not go a little funhouse-style wild?
We have this exact Caroma toilet-sink combo in our powder room. You wash your hands with the clean water that refills the tank post-flush. It saves space where a sink just isn't possible, and it's an easy way to reuse and conserve water. Plus, it quickly becomes a dinner party conversation piece.
Glass walls around this shower make both the room and the bathing space feel larger than they really are. The sink also leaves a little air in the room.
Where there is not space, there can be light (if you are lucky). It always makes a small space feel more expansive.
Use the corners. This room has just enough space for a tiny sink that doesn't take up any precious floor space.
Clear out all clutter. It's one way to get the most out of a small room. And use the inner walls for storage. I hope that mirror opens up to a deep medicine cabinet with lots of shelves.
The components of this space are squeezed in tightly, but the open shower and clear curtain keep them from feeling squished.