Might want to play with the DTE a bit to get something like I stumbled upon to get the rocks to look like they have algea growth. Also, play with the lights with gel textures to get a real ocean bottom effect. Of coarse, that would be moot depending how deep your ocean scene is. Also, it is pretty devoid of life. You might try finding some photos of fish and use the symetrical lattice to create your own models to put in, or just use the pictures. Good luck, you're off to a great start(better than my first attempts).