Making a graphic novel / manga

[graphicnovelist]

There's a flaw with the floor ^^
My initial interpretation of the water was that it was ground. Maybe you can do something to make it more sea-like? If this is going to be coloured you need not bother.

Do you think this coloring is better?
I am unsure about sea white and ground grey or ground grey and sea white.
Also, did you mean with the first sentence that the horizon line is wrong? (I made a correct perspective grid, so the perspective can not really be off, but maybe the mountains are wrong if I set them on top of the horizon line?)

Is the part i marked in red wrong somehow??