Abstract: A system for lifting and moving heavy loads, especially for use in the installation or removal of offshore platforms, comprising a number of lifting devices (1) which are arranged for mounting on a floating structure (2) which during use floats on the surface (3) of a volume of water (4) beside the load which has to be lifted. Each lifting device (1) comprises a lever arm unit (5) with a first (6) and a second (7) arm projecting in opposite directions from a common mounting point (8), the first arm having a lifting point (11) at its free end for engaging with the load, at least one first container (12) which is connected to the first arm (6) at a point near the said lifting point (11), and which is arranged to receive and discharge a flowable medium and to be submerged in the volume of water (4), and at least one second container (19) which is suspended at the free end of the second arm (7).