Ocean and marine energy refers to various forms of renewable electric energy harnessed from the ocean. There are two primary types of ocean energy: mechanical and thermal. The rotation of the earth and the moon’s gravitational pull create mechanical forces. The rotation of the earth creates wind on the ocean surface that forms waves, while the gravitational pull of the moon creates coastal tides and currents. Thermal energy is derived from the sun, which heats the surface of the ocean while the depths remain colder. This temperature difference allows energy to be captured and converted to electric power. This book presents an overview of ocean energy technology as a source of renewable energy for U.S. Federal sites. It investigates ocean energy resources and new technologies under development to capture that energy spanning: wave energy, tidal energy, marine current energy and ocean thermal energy conversion.