I wonder if things under water can reflect like that? It's almost like you've got two water levels right now.
The top water level shifts works for me, you understand what it is instantly. With a wave animation it would look awesome.
The depth (distance) in the image should work much more to your advantage, water is usually quite *foggy* so some ambient light would do the trick.
I'd like to see a hue shift into green. since you've only got 16 colors, make em count.