The page shows three variables:

Significant wave height – The height of every wave is different. The buoys record the rise and fall of the water surface approximately every half a second. We then determine the significant wave height over a 20 minute period. The significant wave height is the average of the highest one-third of the waves. Therefore, it may seem a bit higher than you would estimate by eye. There will be waves both higher and lower than the significant wave height. As a general rule the maximum wave height will be approximately 1.8 times the significant wave height (e.g. if the significant wave height is 2m, the maximum wave height will be approximately 3.6m).

Peak period and direction – The period is the time (in seconds) between wave crests. Just like wave height the period and direction (provided relative to true North) of individual waves vary. The lateral motions of the floating buoy enable us to measure these quantities. They are termed “peak” because they relate to the waves with the most energy. Sometimes you will see these quantities jump significantly in value. This occurs when we have a mixed sea made up of wind-sea and swell. The peak at one time may be the swell and then switch to the wind-sea. This will result in jumps in the peak period and peak direction. Some locations are more impacted by this than others. Wilson’s Promontory is an example of the location which can often have both a SE and a SW swell and a local wind-sea.

Data acknowledgment. This program provides Wave data free for all under Creative Commons Attribution 4 licensing. If you use this data please attribute as “Wave data was provided by the Victorian Coastal Monitoring Program with funding through Department of Environment, Land, Water and Planning, University of Melbourne and Deakin University.”