HSwMS Östergötland (Ögd)
HSwMS "Östergötland" (Ögd), is a submarine of the Swedish Navy named after Östergötland, Sweden. She is the fourth and last ship of the . Development. The submarine design combined the best properties from the and the . 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 of 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 and  Östergötland. After significant upgrades, these two submarines were reclassified to a new . Service history. Between 2000 and 2004, "Östergötland" and "Södermanland" underwent extensive modifications, were extended by 12 meters 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.