Really interesting concept and I loved the no-UI approach! It felt quite atmospheric with the rain and minimalist audio. I felt like there should be some indicator for how much time had passed - if you wanted to keep the no-UI theme you could maybe have the scene gradually get lighter as the sun comes up, or ease the rain up over time?
There is also a bug when you finish the game, go back to the main menu and start a new game, it instantly jumps back to the end game screen.
Also a fun meta-game is seeing how many boats you can crash into each other :]