Abstract: The invention pertains to a heave compensation system for continuous operation on a floating vessel (1), the system comprising at least one buoyant body (11), at least one lever arm (10) for arrangement in a generally horizontal plane, pivotal means capable of limited rotation about a horizontal axis and arranged to connect one end of the lever arm to the buoyant body (11), at least one hinge (13) connected to an intermediate point on the lever arm (10) and capable of allowing limited rotational movement of the lever arm (10) in a vertical plane, means to attach the hinge (13) to the floating vessel (1), and at least one counterbalance weight (12) connected to the lever arm (10) on the side of the hinge (13) away from the buoyant body (11), whereby the inertia of the counterbalance weight (12) resists heave movements of the buoyant body (11) relative to the floating vessel.