Sweden's Near-Miss Submarine: HSwMS Nordkaparen

HSwMS Nordkaparen, a Draken-class submarine of the Swedish Navy, was launched on 8 March 1961 at the Saab Kockums shipyard in Malmö and commissioned on 4 April 1962. On 18 September 1980, during a speed test, Nordkaparen was underwater, using a hydrophone, and was called by a navy helicopter to verify if another submarine was present for a simultaneous test. Nordkaparen announced that it was alone, surfaced for safety reasons, and just then, an unidentified submarine passed beneath the Swedish submarine by just a few centimeters, triggering a two-week submarine hunt to identify the vessel. Today, HSwMS Nordkaparen is preserved as a museum ship at the Maritiman maritime museum in Gothenburg, Sweden.

Sources: Wikipedia, OpenStreetMap, Wikidata, Wikimedia Commons