A water stream is “looping-the-loop” on the inside of a vertical, circular track made from an aluminum tubing cut along its length. The apparatus demonstrates the effect of centripetal (centrifugal) forces much more dramatically than when a ball is used. Although the track is only34-in. wide and only38-in. deep, the water is completely confined to it even at the uppermost portion of the loop. The water inside the loop can drive a small paddle wheel, and small boats can make the loop when dropped on the water stream at the bottom of the track. The apparatus has a built-in pump for pumping the water from the reservoir in the base of the apparatus to the starting point of the track.