The field observation in deep seas was started at Iwaki off-shore wave observation station (h=-154m), 42km off the Pacific coast of Japan, to get the knowledge of the directional wave properties. This paper shows the properties of the directional wave spectra obtained at Iwaki during 2 years.
　The properties of directional wave spectra at Iwaki can be described by the climatic state. For example, multiple peaks appear in the estimates of directional wave spectra under the simultaneous occurence of complexed phenomena in weather.
　The representative wave direction, such as mean direction, cannot indicate the direction of the most dominant peak in multi directional seas, because it's also influenced by the other peaks.