"It is almost totally silent, radiates virtually no heat and is constructed entirely from non-magnetic metals. Meet the U212A -- an ultra-advanced non-nuclear sub developed by German naval shipyard Howaldtswerke Deutsche Werft, who claim it to be "the peak of German submarine technology." And few would argue. The super-stealth vessel is the first of its kind to be powered by a revolutionary hydrogen fuel cell that lets it cruise the deep blue without giving off noise or exhaust heat." (Quoted from article)