National Geographic had this on last fall or winter, it is amazing how much there is out there to learn. The German Sub Fleet was actively working on and had designed Stealth Subs that could not be detected.
On June 23, 2010 they are going to again broadcast this special.
This link will take you to the National Geographic site and you can see a preview video of the show and the sub.
http://channel.nationalgeographic.com/e ... s/06569_00