Lifting balls are used to lift loads, thanks to Archimedes' principle.

It is made up of a sturdy bag capable of retaining air, the loads lifted in this way can be moved horizontally on the bottom or sent to the surface.

If we are talking about open balloons, the bag must have a shape that does not allow air to escape once it reaches the surface.

There is also always a fine adjustment valve which, once adjusted, allows a constant volume of air to be maintained and therefore the load to rise at a constant speed. In the case of a balloon only partially filled and in the absence of such a valve, the speed of ascent increases as the balloon rises since the air, according to Boyle's law, expands as the pressure decreases.

The volume of the bag determines its lifting capacity: a 100 liter bag can, for example, lift a weight of approximately 100 kg. Since according to Archimedes' principle the body to be lifted already receives an upward thrust equal to the weight of the water it displaces, a bag is therefore able to bring to the surface objects with a mass greater than the thrust it can develop.