I think possibly a little guide for at least just where the first treasure chest is could help, then it could maybe be left out for the others so the player has to find them. I was not able to get too far because for some reason I found something confusing about the game initially, so I might come back to this one and play it again later. Maybe there's something about the beginning instruction in-game that's a bit off, because it made more sense to me from the itch.io page itself instead.
Other than that I really think the game is pretty interesting in terms of the control of the ship and the arrangement of things, nice job on the game!