The German Navy’s new Type 212 is one of the most advanced non-nuclear submarine designs in the world. It uses fuel cells to extend underwater endurance.

Introduction

The submarine threatened the major naval powers in two World Wars with loss of control of the seas. This threat resulted both from the inherent capabilities of a revolutionary new weapon of war, and the inability or the reluctance of the major naval powers to anticipate this threat and prepare innovative and effective antisubmarine measures to counter it in peacetime. When first faced with unrestricted submarine warfare, Britain in World War I, and Britain, the United States, and Japan in World War II all suffered grievous losses, especially to their merchant marines, which were to varying degrees their economic lifelines, as well as their means of deploying military forces to distant shores. In two successive Battles of the Atlantic against German submarines, the Allies eventually reestablished sea control after enormous effort, while in the Pacific during World War II, the Japanese Navy suffered grievous losses to American submarines, lost control of its sea lines of communication, and was strangled as a result. Furthermore, the victory of antisubmarine over submarine forces in the second Battle of the Atlantic proved short-lived, as the end of World War II saw the deployment of new German U-Boats which largely returned to the submarine its recently lost advantages over antisubmarine forces. As the Cold War began, the Soviet Navy adopted these new submarine technologies and the U.S. Navy faced anew the task of developing an effective response to a new submarine challenge in peacetime.

via The Third Battle: Innovation in the U.S. Navy’s Silent Cold War Struggle with Soviet Submarines