This paper deals with systems and equipment to put onboard ships meant for water desalting. The ship is rigged to work offshore, either slowly sailing or, usually, being afloat motionless. The ship is a slightly modified liquid gas carrier. Of course, it also holds both modular and dismountable seawater desalting machines and freshwater handling facilities for storage, transshipment and conveyance/transfer towards the shore. Raw water is processed by one of the three systems: multi-stage flash, reverse osmosis and the last one which will probably make a breakthrough soon. The LNG-carrier is of 127,500 m(3) LNG cargo class. The total daily volume of freshwater produced is 120,000 m(3). The water is continuously conveyed to the shore through smaller aqua-tanker shuttle service (originally 21000Tdwt crude-oil tankers). The energy needed to run the plant is LNG. The author has also designed a new type of ship, similar to the LNG-carrier, but meant entirely for seawater desalination industry. Before its conveyance to the shore, the water is stored inside the ship's tanks, the inner of which is covered with huge bags of geomembrane plastic liners. The inner surface of the tanks of freshwater conveying aqua-tankers are similarly lined with polyolefin membranes. During freshwater transshipment, the two ships are sailing side to side, using the so-called 'ship-to-ship-transfer' system. The author called this plant as Aqua Tankerborne Desalination Plant, and the system with a new ship, i.e. not modified one, as Shipborne Seagoing Seawater Desalination Plant.