The DUKW was designed by Rod Stephens Jr., Dennis Puleston, and Frank W. Speir. Developed by the National Defense Research Committee and the Office of Scientific Research and Development, it was initially rejected by the armed services. When a United States Coast Guard patrol craft ran aground on a sandbar near Provincetown, Massachusetts, an experimental DUKW happened to be in the area for a demonstration scheduled to take place a few days later. Winds up to 60 knots (110 km/h), rain, and heavy surf prevented conventional craft from rescuing the seven stranded Coast Guardsmen, but the DUKW had no trouble, and the military opposition melted. The DUKW would later prove its seaworthiness by crossing the English Channel.
Source: Galveston Ducks