Tides, waves and currents can be used to produce electricity. Although still at the research and development stage and not yet commercially available, promising ocean technologies include:

Wave energy, whereby converters capture the energy contained in ocean waves and use it to generate electricity.

Tidal energy, produced either by tidal-range technologies using a barrage (a dam or other barrier) to harvest power between high and low tide;

Salinity gradient energy, arising from differing salt concentrations, as occurs where a river empties into an ocean.

Ocean thermal energy conversion, which generates power from the temperature difference between warm surface seawater and cold seawater at 800–1,000 metres depth.