Bungee jumping is an activity that involves jumping from a tall structure while connecte to a large elastic cord. The tall structure is usually a fixed object, such as a building, bridge or crane; but it is also possible to jump from a movable object, such as a hot-air-balloon or helicopter, that has the ability to hover over one spot on the ground; fixed-wing aircraft are unsuitable because they only stay aloft when moving rapidly forward. The thrill comes as much from the free-falling as from the rebounds.