NOVELTY - A wave-powered desalination system, comprises: a wave-energy-converter subsystem configured to convert power carried by waves propagating on a body of water into mechanical power; a pressurization subsystem configured to pressurize an input seawater flow in at most two steps by at most two pressurization stages; a reverse-osmosis chamber including a membrane having a set of passages disposed in it; an energy-recovery subsystem; and passive conduits configured to carry the input seawater.    USE - The wave-powered desalination system is useful in a method for desalinating seawater (claimed).    ADVANTAGE - The wave-powered desalination system has high efficiency and high recovery rate.    DETAILED DESCRIPTION - A wave-powered desalination system, comprises: a wave-energy-converter subsystem configured to convert power carried by waves propagating on a body of water into mechanical power; a pressurization subsystem configured to pressurize an input seawater flow in at most two steps by at most two pressurization stages; a reverse-osmosis chamber including a membrane having a set of passages disposed in it, the reverse-osmosis chamber configured to receive the pressurized seawater and divide the pressurized seawater, via the membrane, into a permeate flow of purified water and a pressurized brine flow that carries away particles that did not pass through the membrane; an energy-recovery subsystem configured to capture power carried by the pressurized brine flow that exits the reverse-osmosis chamber and to deliver the captured power to the pressurization subsystem; and passive conduits configured to carry the input seawater, the pressurized brine and the purified water between the body of water and components of the wave -powered desalination system without changing a pressure, a composition or a magnitude of a flow of each of the input seawater, the pressurized brine and the purified water. An INDEPENDENT CLAIM is included for a method for desalinating seawater with a wave-powered desalination system which involves: converting power carried by waves propagating on a body of water into mechanical power via a wave-energy-converter subsystem; pressurizing an input seawater flow in at most two steps by at most two pressurization stages; receiving the pressurized seawater and dividing the pressurized seawater, in a reverse-osmosis chamber including a membrane having a set of passages disposed in it, into a permeate flow of purified water and a pressurized brine flow that carries away particles that did not pass through the membrane; and capturing power carried by the pressurized brine flow that exits the reverse-osmosis chamber; delivering the captured power to the pressurization of input seawater, where the pressurized brine and the purified water are carried between the body of water and components of the wave-powered desalination system by passive conduits without changing a pressure, a composition or a magnitude of a flow of each of the input seawater, the pressurized brine and the purified water.