Original Image: Perhaps too much uninteresting foreground? So, we'll start here...
Crop 1: trimmed off a bit of the rocks, still leaving a base for the photo and an overall similar structure, although slightly squarer.
Crop 2: Further trimming of the rocks, squaring the image and focussing now on the groynes, sea and ruins. May suffer from not having a base to sit on. I think it's stronger than the original, but not sure why.
Crop 3: Completely focus on the shapes of the sea and the groynes, with some small fishermen as interest top left. No sky. Completely different feel. I like this one.
Crop 4: The next logical step - all about the shape of the sea and groynes, and now it feels a little claustrophobic perhaps, so I tried to offset that with leaving perhaps more sea on the right than I would normally, to create space to imagine the sea extending further out.
I am sure there are more (like a vertical crop, focussing on the more abstract shape of the groynes), but I wanted to leave some for you guys...
Thoughts and comments welcomed.