Square waves form when two wave systems collide, creating dangerous ocean patterns that threaten boats and swimmers.

Outdoor water tanks have become a staple of productions big and small seeking to recreate scenes of violent ocean ... a tidal wave like that in "The Impossible" (2012). Helming the storm in ...

Another atmospheric river storm packing heavy rain ... and never turn your back on the ocean!" the weather service warned. Large breaking waves of 20 to 30 feet, up to 45 ft, are expected Thursday ...