The sea does not have nice and smooth colour/shade graduations anymore. Nor does it have a decent water texture. It now looks like a badly tiled bathroom floor of various shades of grey, white and blue - with the tiles being a full square mile each! Anyone suggest anything that might be the issue? Not had this problem on any other PC before.
Most likely a problem with this rather shitty GeForce GTX745 rather than the game itself.

Might find the answer myself though, if I do I'll post it up!