Swedish product designer Richard Stark made this flipper for amputees who would like to use their legs more effectively while swimming. It's made so that it distributes forces to the sides, rather than the tip of the leg. The angle of the flipper can be changed to allow for different strokes. Video at the link.
Link via Fast Company | Photo: Yanko Design | Designer's Website
I saw a program on PBS maybe a year ago called Design Squad. There was a double amputee who had the kids design her a "mermaid" flipper, so she could swim and perform.
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