Looking up at the huge white vertical expanse of the barrier she had a moment of vertigo and put a hand on a railing just to steady herself. Then she realized that she was rock solid. It was the barrier itself that was moving. They’d already flooded its dry dock and set it afloat. The whole thing was bobbing ever so slightly, restrained by the 240-meter-long arms, but, thanks to those ball-and-socket joints, free to move up and down.