Incredibly cute and polished! The art and music pair together perfectly, and there's an organic sense of direction around the levels.
My main critique is the platforming physics. I did like that water and land controlled differently. But the land acceleration while running felt difficult to predict as it ramped up. And the sinking speed underwater seemed slow (at least in the context of a platformer).
But it's a well-made game with a good amount of content otherwise.