I believe that if the green rounded piece at the tip is supposed to be circular from a front view, it would look more horizontaly squashed from the current side view.
Some of the rivets on the fin have their lightened parts reversed, I am not sure if it fits the direction of the light.
Maybe the three lighter shades of the wood surface shouldn't be so warm? It is a deep underwater scene, and the water would suck up almost all the red component of the light down there, the wood would get a sickly olive or some other non-red hue. However, that is open to artistic choice I think

Also, someone will probably give you better advice than me regarding the wood grain/texture that might be improved, but regarding the shape of the planks, I think they could show the curvature of the oval body instead of being rectangular all the way. I think I liked the brightness values of the wood in the first pass before the texturing.
Glass, glass is hard, take a look on what eishiya and Pistachio helped me with on another thread, perhaps it will help you:
https://pixelation.org/index.php?topic=26545.msg198345#msg198345Overall I like it, specially the palette, the parallax idea for the underwater background (it will be parallaxed right?) and the fact it is that it is already very readable and non ambiguous, leaning more on symbolism then realism as is proper for a game-y sideview piece.