Observing a buoy in the ocean shows that the buoy moves up and down but does not move side by side, i.e. towards or away from the shore. This is because the water wave causes the buoy to move in a circular direction as the water in the wave moves in circular orbits. As the buoy rises up the peak of the wave(compression), it is also being pushed forward, but as the buoy falls into the trough of the wave(rarefaction) it is being pulled backwards. This results in a net 0 displacement of the buoy side by side, and we observe the buoy as moving up and down. Furthermore, the water in the wave is not displaced, as the wave is longitudinal.
However, this process is disrupted in more shallow waters, as the presence of the bottom(the floor of the ocean) affects the circular motion of the water, resulting in the water(and the buoy) being pulled towards the shore, if that is in the direction of the wave.
