the sun in the back isnt....round....if thats suppose to be a sun. also to make it seem hawaii ish ands tuff, make the sun and water undulo. and maybe put a small relfection int he wtaer. one of of how to do that, make them bottom=blue, top 2 layers are this
trans light blue
trans(reflectedcolor)
blue
blue
blue
your would have a lot of trans black/grey