Good cloud brush you used, though it'd be nice to know where it came from. the size and placement of the character is good for this wall. it conveys well how vast the ocean is.

for the rest, you should learn how to paint the sky, and blend the gradient, unless you don't have many clouds. the reason for this is, when there are large clouds like that, often there are a lot of thin stratus clouds in the sky. and they break up the smoothness of the natural color gradient. this is ok, but try that in the future.

you used too much gaussian blur on the duplicate layer of the seagulls. a little would have been fine, or maybe a little radial blur, but you made them look radioactive here. radioactive seagulls are do not want!

the ocean is plain as mentioned. a few highlights and shadows could change that fairly easily. also it is too flat on the top. always give the horizon of an ocean of large flat area a slight curve. and blur the edge a tiny bit. too the very edge of viewing should be darkest, because the details blur, and no highlights are discernible.

good luck.