Taken from the BOM site.
* Sea waves: waves generated by the wind blowing at the time, and in the recent past, in the area of observation.
* Swell waves: waves which have travelled into the area of observation after having been generated by previous winds in other areas. These waves may travel thousands of kilometres from their origin before dying away. There may be swell present even if the wind is calm and there are no 'sea' waves.
* Wave period: the average time interval between passages of successive crests (or troughs) of waves.
* Wave Height: Generally taken as the height difference between the wave crest and the preceding trough.
* Wave Length: The mean horizontal distance between successive crests (or troughs) of a wave pattern.