With a new hypermodern sonar system and advanced computer technology, the Neptun was a top-class submarine. In 1981, she found herself amid a political and military game of nerves, when the Soviet submarine U 137 went aground in the Karlskrona archipelago.
The budget for the construction of the Swedish navy's first submarine, the Hajen, which was launched in 1904, was around SEK 400,000. The budget for the Neptun, which was placed in service in 1980, amounted to about half a million kronor.
Much had happened in the Swedish submarine fleet in just over 75 years.
However, the Neptun was no ordinary submarine. She was the second of the three that were built of the so-called Näcken class (the other two were named Näcken and Najad). The fore and aft components were manufactured at the Karlskrona naval dockyard while the middle section and assembly of the parts were done at the Kockum dockyard in Malmö.
When completed, the Neptun was nearly 50 meters long and weighed about 1,000 tonnes. Her motto was "Rex Maris" – Latin for "the Ocean's king" – and the submarine had truly royal capabilities with its world-leading onboard technology. The Neptun's completely new sonar system had considerably greater capacity than the systems that had been used by the Swedish navy earlier. She had eight torpedo boats and a fully computerised combat management and fire control system.
The Neptun and U 137
The 1980s was the decade of antisubmarine warfare in Sweden, and in the autumn of 1981, the Neptun was thrown into the midst of the Cold War. At around 8 p.m. on Tuesday, October 27, 1981, the Soviet submarine U 137 went aground at Torumskär in the Gåse fiords. The attention of the whole world shifted quickly to the Karlskrona archipelago and for a week and a half followed a political nerve game at the highest level between Sweden and the Soviet Union.
The incident, which has been called "Whiskey on the rocks" since U 137 was a submarine of the so-called whiskey class, was red-hot news item in the autumn of 1981. It was also a period of risk-filled military games between Sweden and its powerful neighbour to the East, in which the Neptun played an active role. Later, her captain at the time said that his submarine had prevented the Soviet tow-boat from entering Swedish waters and fended it off.
Retirement in 1998
During the 1980s and 1990s, the Neptun was used for reconnaissance and antisubmarine warfare. In 1998, it was time for her to retire from the fleet. For several years, the Neptun was kept in the naval dockyard at Karlskrona, but in 2007, she was gifted to the Naval Museum. Later the submarine underwent a renovation, and when the doors to the Naval Museum's submarine hall were opened to the public in June 2014, the Neptun became a visitors' favourite. Quite evidently, all of her equipment and interiors have been preserved and they provide an unusual glimpse of what it would have been like to live and work in a submarine at the height of the Cold War.