#crestless_wave__crestlesswave__swell  the undulating movement of the surface of the open sea
  supertype:  moving_ridge__wave  one of a series of ridges that moves across the surface of a liquid (especially across a large body of water)
  subtype:  heavy_swell__ground_swell  a broad and deep undulation of the ocean

No statement uses or specializes crestless_wave; click here to add one.