Abstract: An elevator for transporting a load between upper and lower elevations includes a shaft containing liquid therein between the elevations. A buoy accommodates the load to be moved and transports the same within the shaft. A buoyancy control controls the buoyancy of the buoy to cause it to ascend and descend in the shaft. The buoyancy control includes a chamber which is formed in the buoy and which communicates with the liquid in the shaft. A gas control supplies gas under pressure to the chamber for expelling liquid therefrom whereby the buoyant forces acting on the buoy are increased and for venting the gas in the chamber for causing liquid to enter the chamber whereby the buoyant forces acting on the buoy are reduced. The gas control includes descent/ascent protection means for limiting the amount of gas vented from/to the chamber thereby limiting the maximum degree of negative/positive buoyancy of the buoy.