Soviet submarine S - 363 Soviet submarine " S - 363 was a Soviet Navy of the Baltic Fleet , which became famous under the designation U 137 " when it ran aground on October 27 , 1981 on the south coast of Sweden , approximately 10 km from Karlskrona , one of the larger Swedish naval bases . The ensuing international incident is often referred to as " Whiskey on the rocks " . " U137 " was the unofficial Swedish name for the vessel , as the Soviets considered names of most of their submarines to be classified at the time and did not disclose them . Standoff . In October 1981 , the Soviet submarine " S - 363 " accidentally hit an underwater rock about 2 km from the main Swedish naval base at Karlskrona , surfacing within Swedish waters . The boat ' s presence coincided with a Swedish naval exercise , testing new equipment , in the area during the same days . Swedish naval forces reacted to the breach of neutrality by sending an unarmed naval officer aboard the boat to meet the captain and demand an explanation . The captain initially claimed that simultaneous failures of navigational equipment had caused the boat to get lost ( despite the fact that the boat had already somehow navigated through a treacherous series of rocks , straits , and islands to get so close to the naval base ) . The Soviet navy would later issue a conflicting statement claiming that the boat had been forced into Swedish waters due to severe distress , although the boat had never sent a distress signal , but rather , attempted to escape . The Soviet Navy sent a rescue task force to the site in Sweden , commanded by Vice - Admiral Aleksky Kalinin on board the destroyer " Obraztsovy " ; the rest of the fleet was composed of a Kotlin - class destroyer , two Nanuchka - class corvette s and a Riga - class frigate . Sweden ' s centre - right government at the time was determined to safeguard Sweden ' s territorial integrity . As the Soviet recovery fleet appeared off the coast on the first day , a fixed coastal artillery battery locked onto the ships , indicating to the Soviets that there were active coastal batteries on the islands . The fleet did not turn immediately and as they came closer to the territorial limit the battery was ordered to go into war mode on its targeting radar , turning it from a single frequency mode to a frequency - hopping mode . The Soviet fleet reacted almost immediately and all vessels except a heavy tugboat turned and stayed in international waters . Swedish torpedo boats confronted the tugboat , which left as well . The Swedes determined to continue investigating the circumstances of the situation . The Soviet captain , after a guarantee of his immunity , was taken off the boat and interrogated in the presence of Soviet representatives . Additionally , Swedish naval officers examined the logbooks and instruments of the submarine . The Swedish Defense Research Agency also secretly measured for radioactive materials from outside the hull , using gamma ray spectroscopy from a specially configured Coast Guard boat . They detected something that was almost certainly Uranium - 238 inside the submarine , localized to the port torpedo tube . Uranium - 238 was routinely used as cladding in nuclear weapons and the Swedes suspected that the submarine was in fact nuclear armed . The yield of the probable weapon was estimated to be the same as the bomb dropped over Nagasaki in 1945 . Although the presence of nuclear weapons on board the S - 363 was never officially confirmed by the Soviet authorities , the vessel ' s political officer , Vasily Besedin , later confirmed that there were nuclear warheads on some of the torpedoes , and that the crew was ordered to destroy the boat , including these warheads , if Swedish forces tried to take control of the vessel . As the Soviet captain was being interrogated , the weather turned bad and the Soviet submarine sent a distress call . In Swedish radar control centers , the storm interfered with the radar image . Soviet jamming could also have been a factor . As the Soviet submarine sent its distress call , two ships coming from the direction of the nearby Soviet armada were detected passing the limit headed for Karlskrona . This produced the most dangerous period of the crisis and is the time where the Swedish Prime Minister Thorbjörn Fälldin gave his order to " Hold the border " to the Supreme Commander of the Swedish Armed Forces . The coastal battery , now fully manned as well as the mobile coastal artillery guns and mine stations , went to " Action Stations " . The Swedish Air Force scrambled strike aircraft armed with modern anti - ship missiles and reconnaissance aircraft knowing that the weather did not allow rescue helicopters to fly in the event of an engagement . After a tense 30 minutes , Swedish Fast Attack Craft met the ships and identified them as West German grain carriers . The boat was stuck on the rock for nearly 10 days . Finally on November 5 it was hauled off the rocks by Swedish tugs and escorted to international waters where it was handed over to the Soviet fleet . Interpretations . At the time , the incident was generally seen as a proof of widespread Soviet infiltration of the Swedish coastline . In an interview in 2006 , Vasily Besedin , the political officer on board , gave a different picture . The vessel had dual navigation systems , a well - trained crew and the captain Pyotr Gushchin was amongst the best . On board was staff officer Joseph Avrukevich who was trained in security techniques . Besedin claimed the incident was caused by an error in calculations by the navigation officer . The area in which the Soviet submarine ran aground was at the time a restricted military zone where no foreign nationals were allowed . The exact location served as one of only two routes that could be used to move bigger ships from the naval base in Karlskrona to open water . This incident is popularly known in the West as " Whisky on the rocks " . In the Soviet Navy the submarine type came to be known as " Swedish Komsomolets " , a pun on both the incident and the then widespread tendency to give the submarines Komsomol - themed names .