A power generator utilizing gases and the gravitational force as efficiently as the buoyant force which act on an apparatus in a natural or man-made liquid medium and convert such forces into mechanical energy. The power generator includes methods for a plurality of weighted uniquely configured variable density containers which ascend and descend in a primarily vertical plane and which drive one or more chains, belts or conveyances with rotating sprockets or pulleys on horizontally aligned shafts in primarily a vertical arrangement upon such apparatus. The chains, belts or conveyances driven by the movement of the containers rotate the sprockets or pulleys (FIG. 1) and their associated shafts in both the ascending and descending motion creating mechanical power. Such power can be used to turn electrical generators or other mechanical machines which necessitate such power input.