The ship and sky are black and white while the ocean has a blue overlay. Or the photo was originally color and the ship and sky were layered black and white. It is a striking effect, though I might have upped the contrast on the ship.
Agnes: if we had a room with thick ropes curling on the floor, reaching from wall to wall, to give you the feeling of being on a boat. You could even have an aquarium were water is bubbling, making it look like a window.