Submarine

The modern submarine is the ocean's invisible predator — a pressure-welded steel cylinder that slips beneath the surface and becomes practically undetectable to anything that cannot close to active sonar range. German Type VII U-boats terrorized the North Atlantic from 1939 to 1943, sinking millions of tons of Allied shipping and nearly strangling Britain's supply lines before improved convoy tactics and radar turned the tide. A submerged submarine attacks with electric torpedoes that leave no visible wake, striking the thinnest part of a hull below the waterline where a single detonation can break a ship's keel. Her vulnerability is depth-charge attack, sonar-equipped escorts, and the need to surface or use her snorkel to recharge batteries. In the game she is invisible while submerged, lethal against all surface ships, but detected and destroyed by destroyers and anti-submarine aircraft once she gives away her position by attacking.