USS Ronald Reagan, a newly constructed $6.2 billion dollar aircraft carrier, sank after being hit by multiple torpedoes.

Fortunately, this did not occur in actual combat, but was simulated as part of a war game pitting a carrier task force including numerous antisubmarine escorts against HSMS Gotland, a small Swedish diesel-powered submarine displacing 1,600 tons. Yet despite making multiple attacks runs on the Reagan, the Gotland was never detected.

This outcome was replicated time and time again over two years of war games, with opposing destroyers and nuclear attack submarines succumbing to the stealthy Swedish sub. Naval analyst Norman Polmar said the Gotland “ran rings” around the American carrier task force. Another source claimed U.S. antisubmarine specialists were “demoralized” by the experience.

The Gotland class does possess many other features that make it adept at evading detection. It mounts twenty-seven electromagnets designed to counteract its magnetic signature to Magnetic Anomaly Detectors. Its hull benefits from sonar-resistant coatings, while the tower is made of radar-absorbent materials. Machinery on the interior is coated with rubber acoustic-deadening buffers to minimize detectability by sonar. The Gotland is also exceedingly maneuverable thanks to the combined six maneuvering surfaces on its X-shaped rudder and sail, allowing it to operate close to the sea floor and pull off tight turns.