Well done, and also quite the good puzzle design, I also really liked the art style you were going for (even if I initially had trouble to see the water as water :D). Overall without too much of an tutorial you managed to make it easy to understand how the mechanics work without explaining too much to allow players to find out for themselfs :)
As others have mentioned WASD would have been better than the arrow keys :)
Overall quite the impressive entry given the limited timeframe :)