Hm... looks amazing! your sea and sky look wonderful.
one or two things id like to point out, you're missing some reflections and shadows (You mentioned it missing something, I do believe that's it). other than that, Id just watch your use of the smudge tool (It's incredibly useful, and just as dangerous). as well, make sure the water-level comes ABOVE the silhouetted landmass' base. you probably wouldn't be able to see the beach from this angle, due to lighting and the swell of water. (I cant tell if that's a continuation of your beach or the water not meeting like it should ;D)
but other than that, REALLY good! @u@