Systems, methods, and apparatus for desalinating water are provided. A vessel includes a water intake system, a reverse osmosis system, a concentrate discharge system, a permeate transfer system, a power source, and a control system. The concentrate discharge system includes a plurality of concentrate discharge ports. A water intake system installed on a sea-going vessel positioned on the surface of a body of water includes an apparatus for taking up seawater from the body of seawater. The apparatus includes a water intake member, a water intake positioned on the water intake member, and an impingement, entrainment, and entrapment mitigation device at least partially surrounding the water intake and including a plurality of apertures sized to prevent entry of marine organisms into the water intake. A method of desalinating water on a sea-going vessel positioned on the surface of a body of seawater includes the steps of intaking seawater from the body of seawater into the vessel through a first screen including a plurality of apertures sized to prevent entry of marine organisms into the water intake, and removing salt from the seawater taken into the vessel to yield desalinated water and a concentrate.