After the mid-life upgrade programme (MLU), HMS Gotland, set sail for the first trials. After the operation tests of the systems were completed at the dock, the ship was navigated for the tests that should be carried out at open sea. During the trials, new systems integrated under the integration will be tested for the desired capacity.
Submarines built between 1990 and 1997, had previously undergone minor modifications before. Up to 20 system, which reached the end of their economic life, were replaced with new ones. Together with the effectiveness of the submarine, situational awareness and safety level were also increased. The bodies of the platforms were extended two meters and the Stirling Air Independent Propulsion System was integrated. In addition, a new mast system equipped with modern electronics instead of the traditional periscope was added to the submarine.