The chapter explores the origins of ocean power, the three types of energy captured from the oceans, the energy from the motion of the waves, the energy from the tides, and from using temperature gradient in oceans. The main onshore and offshore ocean wave technologies are described. Tidal origins, fundamentals, and power-generating plants are described, followed by a discussion on their environmental impact. Finally, the basics of utilizing ocean thermal energy are presented. A case study on wave power is presented.