U 137 - Whiskey on the Rocks

On 27th of October 1981 a submarine emerges in the archipelago of Karlskrona. It runs aground in Gåsefjärden that lies about 10 kilometres southeast of Karlskrona. Attempts are made to free the submarine with the help from its diesel engine, but it doesn’t work.
A fisherman discovers the boat the day after, when he is out fishing on the sea. When he gets home, he instantly calls the naval base. The military arrives and places its boat next to the submarine. The Soviet naval flag is set on the top of the tower near the boats, and some members of the submarine’s crew has climbed up the tower. Commander Karl Andersson boards the submarine. No one of the Soviets speaks English, so Andersson tries German instead, which gets him introduced to the captain, Anatolij Gushchin. The submarine turns out to be from base Leiepaja. The Soviets say that they’ve ended up in the wrong place after problems with the navigation system and some other things.
The Soviet Union contacts Sweden’s minister for foreign affairs, which at that time was Ola Ullsten. The Soviet Union wants to send a ship to Sweden to pick up the submarine, but their request is denied. Instead, Sweden will tow the boat outside the Swedish boundaries. During the evening of the 28th of October the submarine is allowed to contact its base, but the whole conversation is being intercepted by the Swedish military.
A salvage ship from the Soviet Union is being sent out together with twelve other ships to get the submarine, not caring about the ban. Sweden stops them from succeeding.
The 29th of October another submarine is spotted, but it disappears.
When the Swedish Defence Research Agency examines the boat, they are threatened by the Soviets in the tower, who are armed with automatic weapons. The Swedish investigators believe that there may be Uranium aboard. Sweden wants to question the captain, and eventually the Soviet Union allows it, given that two Soviet diplomats will be present. Yet the captain refuses. Secretly Sweden measures the radioactivity at the boat, and afterwards they are quite sure that there is Uranium-238 somewhere on it. The military tows the submarine and gives it over to the Soviet Union. By now they are rather certain that the Soviets had nuclear weapons aboard.
2006 a submarine’s political officer is interviewed. He says that the boat, the navigation system and everything else worked fine, and that it was the navigating officer’s calculations that had been wrong. He also admits that they had nuclear weapons aboard.
Many people speculate in whether the submarine was in Sweden on a spy mission.