Behold a device called the JetLev flyer (thanks to Wendell Maradonna for bringing it to our attention). The manufacturer opines: “A flexible water supply hose delivers power to the jetpack with pressurized water. It also serves as the tether, enforces a flight ceiling, discourages the pilot from flying over land, acts as a stabilizer, dampens vibrations, and maintains forward heading stability of the jetpack in flight.”