Seawater desalination can be an attractive alternative to ensure a secure source of water. However, the energy requirements for that process are high and can be a problem, mainly in isolated areas. Renewable energies are the best way to supply the energy needs, because can be available near the desalination plants and avoid environmental/availability problems associated with fossil fuels. In this paper two forms of renewable energies particularly suited for desalination are described: wind power and wave power.