The first step in determining the feasibility of a wave-energy conversion device is to assess the available wave energy in a given area. We show the estimation of wave energy from observational wave and wind data. A total of five different methods of wave-energy estimation are presented. One of these methods, which is introduced for the first time, is the estimation of wave energy from observational wind data using the Weibull distribution. This new method of wave-energy assessment is applied to an area near the Hawaiian Islands and compared with other available results. The comparisons show that the theory based on observational wind data produces results that are in overall agreement with previous calculations based on the measured spectral-density of waves, as well as on observational wave- and wind-data.