Gravity waves are waves greater than 1.73 cm. Those waves depend on gravity to provide the restoring force. Like a rubber ball, gravity pulls the wave down, but the momentum of the water causes the crest to overshoot to become troughs and crest again...

Since the circiular motion of water molecules in a wave is nearly friction-free, garvity waves can travel across thousands of miles of ocean surface without dissipating, eventually to break at a distant shore. 

Below: Hills and valleys are forming as a wide open ocean greets us with a firm but friendly force...

(Link to Seafloor-maps)