Vanishing Point

The Vanishing Point filter enables you to clone in perspective, where details recede into the distance along straight lines. You can clone details closer to the camera to replicate them further away, or vice versa. Here it lets us tidy the dark patches under the pier. Go to Filter > Vanishing Point, then grab the Plane Tool and plot a plane along one of the surfaces in the scene. Press S for the Clone Tool and Alt-click to sample, then paint to clone in perspective.