Really cool little game! You did an amazing job of selling the scale of the monster, the ships looking so tiny next to it and the large amount of screen space taken up do such a great job of making it feel unimaginably huge. The minimalist visuals work really well for that too I think, the monochrome black on blue makes it feel like you're just watching shadows under the water which gives it a really nicely ominous mood.
Controlling the monster is a lot of fun - I like that every part of it is able to deal damage, slapping down ships with the tail was really satisfying and the most fun I had in the game. The boss took me out of the immersion a little bit with its long invincibility periods and ridiculously large flamethrower blasts, but it was a fun fight gameplay wise, so I think I'm willing to overlook that :P
I only really have two nitpicks - the first was that the really long chargeup on the breath attack made it feel a bit infeasible to actually use in combat, especially with how easy it was to sink ships by just ramming into them. I feel like it should be reduced a little so the attack actually feels viable to use outside of its arbitrary gates. The other nitpick was that the radar ping sound got a little grating by the end, though that one really is a nitpick as the sound design was in general absolutely brilliant and really helped create this desolate feeling. The kind of ominous pinging is definitely helping to contribute to that, so I wouldn't say to remove it completely, but maybe it needs a little more variation, or to be used a little more sparingly, if the game gets any longer.
I'm honestly not sure where this could go as a longer game - even as short as it is, it feels like a really complete and cohesive package as it currently stands. I suppose a bit more narrative could be interesting? Idk, I'm curious to see where this goes. It's definitely by far my favorite game I've played in this jam so far, really good work.