New German submarinesGerman Navy got two new submarines for the first time since 1975. The both boats are revolutionary design. They are equipped with so-called fuel cell systems, developed since early 70s. The system can convert hydrogen and oxygen into electric energy without noise or exhaust. This enables to stay submarged for weeks, so the monopoly of nuclear powered submarines has been just broken.
The German submarines are also tasked to conduct clandestine SIGINT missions. They are small and maneuverable, so they can operate on shallow waters, with only antennas deployed above the sea surface. It riminds me the interesting talk I had some years ago with the skipper of ORP Dzik, Polish submarine of "Foxtrot" class. He said that always before the periscope was deployed above the surface, they deployed small RWR antenna, to scan the radar frequencies if the sea surface is actually observed by any enemy. It was a routine procedure in Warsaw Pact navies and probably is typical for all the navies in the world.