I think the middle colours work the best because the bottle would change colour under water, but something seems strange in the way the highlight on the bottle cuts off at that angle. and bottom placement seems best too.
I like the color scheme in the middle, it looks most like a submerged bottle. One more thing though, shouldn't the part of the bottle that is underwater look more squiggly due to the distortion from the waves?
thanks, and yeah, I'll have to fix the shine on the bottle in the leftmost 2, I did forget to readjust that after I chopped the bottle in half for the 2 color tones.
I'll try a blue that's not so deep, maybe a dark blue/green.
I'd love some specific suggestions for the island or whatnot, I had abandoned the idea of that as I thought it may look too cluttered.
I've submitted this version. While I completely agree that having a ripple effect on the image below the water line would enhance the image, I just can't pull it off convinceingly enough, in fact, my attempts stuck out like a sore thumb and distracted from the rest of the image 0.o so I left it as is and added a second color option.