The Most Efficient Swimming Propulsion Device Ever

Who do you go to if you want to develop the most efficient swimming propulsion device ever conceived?  Darpa, of course.  That's the Defense Advanced Research Projects Agency.  They bring you simple new innovations, like say, the internet.  Anyway, they've put their minds to work and developed a cool way to send the Defense Dept's swimmers through the water faster.  Thinking a better kind of fins?  Think again.  Check out the video below.