The atmosphere in this game is pretty good, and it looks pretty nice visually. It's really annoying how the camera isn't centered on the jellyfish though.
The Shark AI is also pretty weird. They seem to move incredibly fast, with no way to know if one is nearby outside the screen bounds, and there's also always one shark following you. I think it would've been better if the sharks had instead been able to loose track of you and stop chasing, and would also react to movement. It would also be better if the sharks had some kind of movement pattern that they do when not chasing you. Considering the theme, having audio cues help you figure out where the sharks are would also help improve them.
The light mechanic also doesn't work really well, since you can see sharks and food perfectly fine without it, and it just doesn't feel all the great to use. I think having it where instead the light increased in brightness rather than sized would've been much better.