Just Ducky ... And here is another little wrinkle that enables the modern beach belle to take to the water, literally, like a duck. The gadgets, worn like shoes, are called "swim fins." They are simulated webbed feet that serve not only to increase swimming speed, but also protects milady's little tootsies when out of the water. August 03, 1941. (Photo by Hans Reinhart, International News Photos).