NOVELTY - Desalination of seawater comprises conducting seawater into distillation container (1); vaporizing seawater; condensing formed vapor into distilled water; and conducting distilled water by the help of pump (8) into further use. The seawater is heated and vapor is condensed by the help of heating and cooling mechanism (18) comprising compressor (18c), hot circuit (17, 18a), and cold circuit (11). The energy for vaporizing seawater, condensing formed vapor into distilled water, and conducting distilled water by the help of pump into further use is taken from the kinetic energy of the waves.    USE - Desalination of seawater.    ADVANTAGE - The method is reliable, cost efficient, and multifunctionally ecological. It saves a lot of energy, where all the energy that is needed is obtainable from the sea. The kinetic energy of waves gives all necessary energy to all the actuating mechanisms used in the solution, e.g. to all the pumps, valves, hydraulic actuators, and generators. The natural thermal energy of seawater can be used for cooling and heating purposes in different stages of the desalination process. No outside sources for cooling or heating is needed. All the waste heat can be utilized with heat exchangers because both the features of the heat pump are utilized: both the heat generation and the cooling feature. When the raising of the water temperature to the boiling point is made in two stages, the coefficient of performance is better. All the pumps and actuators can be driven with a varying speed of rotation, which is natural to the energy obtainable from the wave energy. Inexpensive distilled water pipeline from the apparatus to the shore or to another place where fresh water storage is located is provided. The installation size can be smaller than in the conventional distillation systems. The apparatus does not need a lot of maintenance, so that the maintenance intervals can be long.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for apparatus for desalination of seawater.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view illustrating the desalination of seawater.    Distillation container (1)    Pump (8)    Cold circuit (11)    Hot circuit (17, 18a)    Heating and cooling mechanism (18)    Compressor (18c)