At age 11, Benjamin Franklin – already an avid swimmer – invented the world's first pair of swim fins. The first version consisted of wooden oval planks that Franklin held in his hands to give him extra thrust in the water. Franklin also tried strapping boards to his feet, much like sandals, but those foot flippers were too awkward. His lifelong advocacy of swimming led to his induction into the International Swimming Hall of Fame in 1968.
Here's part of what Franklin wrote in 1773: “I made two oval pallets, each about ten inches long, and six broad, with a hole for the thumb, in order to retain it fast in the palm of my hand. … I swam faster by means of these pallets, but they fatigued my wrists.”
Benjamin Franklin, idea man: