The ocean waves data measured at 147°E in longitude and 32°N in latitude by a discus buoy were analyzed. The wave statistics shows that the significant wave heights during the winter were about twice or threefold as large as those observed in coastal sea area, and that the ratios between the wave characteristic parameters and the cumulative distribution of relative wave heights were similar to those obtained from coastal wave data. For rough seas the time variations of the significant wave height and the mean wave direction are closely correlated with the variation of the wind speed and the wind direction on the spot, respectively.
　On the basis of the examination of the relation between the two directional parameters, the long-crestedness and the mean spreading angle, it is deduced that the directional spectra for extreme seas might be unimodal ones which are characterized by a Mitsuyasu type directional function with Smax=10 to 40 or bimodal ones of which two directional peaks differ from each other by less than 90 degress.