Soviet submarine S-363 was a Whiskey-class submarine 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 "Whisky on the rocks". U137 was the unofficial Swedish name for the vessel, as the Soviets considered names of most of its submarines to be classified at the time and did not disclose them.

In October 1981, the Soviet submarine S-363 accidentally hit an underwater rock about 2 km from the main Swedish naval base at Karlskrona. The boat was surfaced and inside Swedish territorial waters. 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 (this 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.