Really solid experience with great voice acting! Mechanics were simple and worked well. The Fish ville signs felt like were misleading few times. Also after the dead family reveal, when entering Fish ville again, during the Coral cutscene something weird happened and Coral floated up from the play area to grey and camera followed. After the dialog was finished it was only grey and I was stuck. But I assume I sacrifised myself. Well done!
As additional tip, I would probably avoid making too big wide areas. I tended to do my exploring by following the walls. If there were really wide area, I would easily miss if there was anything important at the center that I didn't see while swimming by