Abstract: A wave energy converter comprises an acceleration tube (14) attached to a buoyant body (11). An intermediate section of the acceleration tube defines a working cylinder (16), with openings in the acceleration tube above and below the working cylinder allowing unobstructed flow of water between the working cylinder and the body of water in which the acceleration tube is immersed. A working piston reciprocates in the working cylinder. A relief passage at each end of the working cylinder is controlled by the working piston to allow unrestricted flow pass the working piston when the piston moves past a predetermined position at the end of the working cylinder. An energy absorbing device (19, 20) is connected to the working piston. A restoring device (19C, 20C) is provided to apply a return force to the working piston towards the working cylinder, if and when the working piston moves past the predetermined position.