Did you ever see one of these? I remember seeing one back when I still lived in Chicago.... "The Amphicar Model 770 is an amphibious automobile, launched at the 1961 New York Auto Show,[2] manufactured in West Germany and marketed from 1961-1968, with production having ended in 1965. Designed by Hans Trippel, the amphibious vehicle was manufactured by the Quandt Group at Lübeck and at Berlin-Borsigwalde, with a total of 3,878[2][3] manufactured in a single generation. A descendant of the Volkswagen Schwimmwagen,[4] the Amphicar offered only modest performance compared to most contemporary boats or cars, featured navigation lights and flag as mandated by Coast Guard — and after operation in water, required greasing at 13 points, one of which required removal of the rear seat.[2] The Amphicar name is a portmanteau of "amphibious" and "car"." See: https://en.wikipedia.org/wiki/Amphicar
Yes I remember seeing those weird cars around Montreal in the early 60's.. They were not very good as a car or a boat and we all said it was a good idea but needed improving..