Why did you used all those black outlines, even on those little "rugs"? You should remove them, and try to achieve readability by using different colors with higher contrast, cause some characters, and parts of this image are very hard to read. Trees are too generic, and they look more like a blob army. Shark should be longer and slimmer now it looks like a torpedo. If main element here is the building you should make it bigger (there are a lot of good architectural reference for this) and add more elements to it (also find some reference), cause it doesn't look very elite now.
You should definitely add some waves in the water cause now it's too plain.
