https://en.wikipedia.org/wiki/HMCS_C...an_alterations
...On 4 June 2011 the submarine
ran aground in
Nootka Sound during manoeuvres off
Vancouver Island. The submarine collided with the sea floor in 45 metres (148 ft) of water while travelling at a speed of 5.9 knots (11 km/h). The collision opened a 2-metre (6 ft 7 in) hole in the submarine's
bow. Two submariners were slightly injured.
After the grounding incident civilian and military submariners began pre-maintenance work on the submarine, in the expectation of an extended maintenance program. At the time, the process, length and cost of the work was unknown due to existing contracts.... In February 2012, post-collision photos of the dry-docked submarine were published, showing extensive damage to the bow; the media also cited unofficial sources, saying the pressure hull may be damaged beyond repair.
As of July 2014,
Corner Brook began her extended docking work period (EDWP) that was expected to take until 2017 to complete.
On 1 April 2019 the submarine, still in drydock at CFB Esquimalt, caught fire. The fire was extinguished but the cause was unknown.
The vessel was intended to return to service in mid-2020. However, in a March 2020 pressure test of the submarine's ballast tanks, the test team attempted to empty the tanks more quickly using pressured air, leading to over pressurization and a rupture.
The submarine was fully repaired/upgraded and returned to active service on 2 April 2025.
The submarine is expected to remain in service for another nine years following the refit......