HSwMS Södermanland (Söd)

HSwMS Södermanland (Söd) is a Swedish naval submarine, launched in 1988 and currently in active service. She is the third ship of the Västergötland-class submarine and named after Södermanland, Sweden.

Development
The submarine design combined the best properties from the Sjöormen-class submarine and the Näcken-class submarine. Submarines of the Västergötland class had greater submarine hunting capacity than previous classes, partly due to the fact that they were equipped with a new modern submarine torpedo. The submarines in the Västergötland class were able to fire up to six heavy and six light wire-guided torpedoes at the same time against different targets.

The Västergötland class included the submarines HSwMS Södermanland and HSWMS Östergötland (Ögd). After significant upgrades, these two submarines were reclassified to a new Södermanland-class submarine.

Career
Between 2000 and 2004, Södermanland and Östergötland underwent extensive modifications, were extended by 12 m and fitted with air-independent Stirling engines. At the same time, the submarines would be modified to handle international missions with operations in hot and salty waters. The conversion of the two submarines became so extensive that Kockums decided to reclassify the submarines to a new Södermanland class.

During 2022, Södermanland underwent yet another life extension program, in order to be operational until 2028.

As Östergötland was decommissioned in 2021, Södermanland is the only remaining submarine in its class.