What to do when the background is the subject ?? Need some composition tips

People say that while taking photographs there should always be a clearly defined subject as well as a good pleasing background.If you don't have a decent background you could always blur it out or get a tight shot of the subject instead. But what to do when the background is the subject ?? how to compose ?

Below is a shot (OOC JPEG) of an island taken from a moving boat. I like the shot as it is.but what, if any, should i have done differently ??I know the horizon line isn't straight.But that can always be rectified in post.What else ??