Very innovative. The music, art, and gameplay are great. Maybe add some bonuses/upgrades that allow you to see if there are boats or monsters coming? Maybe add some boats with lights so you know they aren't monsters for variety (could do the opposite for some monsters).
This is like the 4th game I've played in the jam using light focusing in different ways. This is mine that does that also: https://itch.io/jam/brackeys-8/rate/1675396