Really fun concept! Good use of the jam theme, I loved it overall, the art and sound design is top notch. I particularly like that the music changes depending on if you're underwater or not. It also felt really polished, I found no bugs.
If I had to give a couple suggestions:
-I would add some more differentiation to each area (I got a little lost sometimes)
-If you expand the game, maybe there could be obstacles/enemies/timed challenges. Also, the movement system is really cool! I would get some crazy speed sometimes around slopes, maybe building a mechanic around that could be cool