At least with regard to significant wave height (rather, describing the sea conditions): It's more useful to describe a "sea state" which is made up of infinit

At least with regard to significant wave height (rather, describing the sea conditions): It's more useful to describe a "sea state" which is made up of infinitely many frequencies, directions, etc. than to have a timeseries of wave elevation at a given point. A snapshot of the overall sea conditions for a given time, if you will. Sea states can be well described by a couple statistical parameters, namely significant wave height (Hs), peak wave period (Tp), and peak wave direction. There are other refining parameters such as the directional spread but Hs, Tp, and direction are quite informative.