Wonderful job! I love the visuals (the shimmer effect on the fish in the background is soo clean). This is incredibly well executed, and my favorite puzzle-platformer this jam. It's got so many unique and polished puzzle mechanics. I wasn't expecting the increase in platformer difficulty in the later levels (especially 16), but it was a welcome challenge. Incredible work!
Some less-than-ideal stuff:
You die when walking off of a block that has spikes on the sides, which can get very frustrating.
The enemies in the later levels don't feel amazing. I think they would be less annoying if they didn't always go directly towards the player. As it stands, it's very easy to get cornered and have to restart the whole level for something that doesn't necessarily feel like the player's fault.
Again, absolutely wonderful job.