DUKWs (affectionately known as 'Ducks') were originally used in World War Two to carry supplies. Rather than loading supplies from big boats onto little boats then onto trucks, troops would simply drop them onto DUKWs. These amphibious vehicles would skim across the water then climb on to the land and drive off. After helicopters were invented, however, Ducks fell out of favor. Today, they're popping up all over the world again – this time for tourists, most recently in New York.
London, for example, they tour sites like Trafalgar Square and Buckingham Palace, then slide into the Thames. Check them out next time you're in San Francisco, West Palm Beach, Florida, Philadelphia, Portland, Oregon, and even Ketchikan, Alaska. RM