[Pernod]

Personally I would probably slice it to a panaromic style.

If the water holds more significants for you, then I'd probably cut the sky in half, and then trim a little water to get the water/dune line to about 2/3rds of the way up the photo (if this looks funny, then trim the water and keep the sky).

Oh, hang on, I just realised what I'm actually thinking... given this has a more fluid feel rather than a object the eye focuses on, I'd stick with the rule of 3rd's. A panaromic (wide but short) style would allow you to do this and keep all the land.