Hawaii's beaches are of great economical and. social value; they serve a variety of purposes and are valuable both to residents and tourists alike. Like in many other parts of the world, many of Hawaii's beaches are in a state of erosion and measures of improvement must be designed to cope with this problem. Although in the past several studies have been undertaken to evaluate Hawaii's beach systems and to analyze possible measures of improvement, this study aims at an in-depth analysis of the physical factors at work in the coastal zone. A thorough understanding of these processes, it is felt, is indispensable for the application of sound and economic measures in stabilizing and maintaining Hawaii's beaches. This paper describes some preliminary results of field studies conducted in Waikiki Beach. The latter beach was chosen because of the pressing need for improvements and because of its convenient location. In order to project this study against the proper background, a short review of the general characteristics of Hawaiian beaches precedes the results of the Waikiki Beach study.