Interesting concept, I did get out of the water but my current controller did not allow me to use the right anonlog and the keyboard was a bit obtuse but I still respect this kind of game.
I did want to try this cuz I have SOOOO many lucid dreams where I either turn into a mermaid or somebody poofs me into one but this was never an idea that came to mind so its a good way to explore this "What if" sanrio