A friend had a best of youtube of a water jetpack. It had a "trailer" for lack of a better word... There was a boat liek capsule thingy that you drag through the water. It sucks up water and feeds it through an embilicle to the backpack and makes a waterjet that will keep you like 30 or 40 feet above the water. the thing was really cool. Used like a V-6 engine or something.