The ocean is never still. Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. The gravitational pull of the sun and moon on the earth also causes waves. These waves are tides or, in other words, tidal waves. It is a common misconception that a tidal wave is also a tsunami. The cause of tsunamis are not related to tide information at all but can occur in any tidal state.