Sometimes the documents from the Patent Office provide some interesting ideas.

An individual named C.E. Gorton applied for a patent for this design on May 14, 1964. Some two years, two months and five days later (July 19, 1966) he actually was granted that privilege. The "Triphibious Vehicle" as it was called, was designed to be a car, a plane, and a boat all-in-one. It had room for two people (tandem), and had one engine that not only provided power to the counter-rotating rotors, but also powered the ducted prop at the rear for motive power on land and while afloat.

What great fun it would be to be able to tell your friends that "I flew south to my favorite fishing spot, drove out onto the lake and caught two absolutely delicious bass off the side of the boat. I didn't even have to get out of the car."