"This sunken tub is lined up perfectly at the same level as an exterior pool of water. The window opens all the way so it looks like a single pool." Design by Garret Cord Werner. Maybe for the master bathroom
One great Hunk of a bath at hotel Mio Buenos Aires, Argentina Argentine artist Mario Dasso hand-carved each bathtub from a single piece of native calden wood, using trees already felled by natural occurrence.
Love the Japanese idea of a window flush with the tub! Nothing says relaxation like a nice soak with the breeze :) (There'd need to be a tree or something though for privacy haha) . there is a Japanese Garden (patio) outside.