Type 212 runs silent on its electic engines and nearly silent on its Fuel cell AIP drive. The electric drive would be quiter than SSNs and as long as they stay on passive sonar searching they are a lethal threat to any surface group. A few years ago the Royal Navy had to halt an exercise off the coast of Norway because of a single Norwegian Ula diesel/Electric Sub [German/Norwegian/French design] had simulated sinking the British Carrier and troop transports, with out being detected.

[en.wikipedia.org]



"The Ula class submarines are among the most silent and maneuverable submarines in the world. This, in combination with the relatively small size, makes them difficult to detect from surface vessels and ideal for operations in coastal areas. During the annual NATO Joint Winter exercise in 2004, the HNoMS Utvær had to be disqualified from the exercise because it kept the entire landing operation at bay.[2] It simply "sank" too many vessels, including the Royal Navy flagship HMS Invincible. The Ula class submarines are regarded as both the most effective and cost-effective weapons in the RNoN."

[tripatlas.com])