Swim Fins - Benjamin Franklin was an avid swimmer from a very young age. Throughout his life he consistently promoted its healthful benefits. At the ripe old age of 11 he invented a pair of swim fins. However, unlike today's foot flippers, these were attached to one's hands. His advocacy for swimming was recognized by his induction into the International Swimming Hall of Fame in 1968.
While the concept of the odometer dates back to ancient times, Franklin did create his own version. The concept was to attach the device near the wheels of a carriage, determine the circumferance of the wheel and the number of revolutions required to travel a mile, and have the device register the distance traveled. http://www.ushistory.org/franklin/info/inventions.htm