Several plans for the disposal of the submarine were made and cancelled before the Site historique maritime de la Pointe-au-Père in Rimouski purchased the boat for preservation as a museum vessel.

The Oberon class were considered an improved version of the preceding Porpoise-class submarines, with a different frame of the pressure hull[3] and constructed from a better grade of steel.

[10] In an effort to take the subs from anti-submarine warfare training to frontline service, Maritime Command developed a refit program that included new sonars, periscopes, communications and fire-control systems.

[31] Onondoga arrived at HMC Dockyard at Halifax, Nova Scotia on 18 January 1982 in preparation for her SOUP refit.

[29] Following the SOUP refit and the introduction of the Mark 48 torpedoes, the Oberons were considered fully operational and counted the same as other offensive fleet units in Maritime Command.

[31] Following the end of the Cold War, the Oberons were retasked, performing patrols on behalf of federal institutions such as the Department of Fisheries and Oceans and the Solicitor General of Canada between 1991 and 1994.

[31] During the Turbot War, the Oberons were tasked with monitoring European fishing fleets off the Grand Banks of Newfoundland.

[34] In May 2005 the Halifax Chronicle-Herald announced that Maritime Command was looking to sell Onondaga for scrap metal, along with three other Canadian Oberons.

[35] Instead of being scrapped, the submarine was purchased by the Site historique maritime de la Pointe-au-Père, Rimouski in 2006, for C$4 plus tax to become a museum ship [fr].

[34] The submarine was towed from Halifax to Rimouski during the summer of 2008, floated onto a temporary marine railway, then hauled up the shore into the final position.

[36] Getting the submarine onto the marine railway required a high tide of 4.6 metres (15 ft), which would only occur during a 2-hour window on 2 August.

[40] Onondaga arrived in Rimouski harbour on time for the 2 August high tide, but a heavy storm prevented the operation from occurring.

[43] As the water receded overnight, the submarine rolled to the right and off the railway, puncturing the outer casing on a nearby boulder.

[45] A fourth and final attempt was made on 28 November; after this, there were no more opportunities before winter struck and froze Rimouski harbour, further damaging the submarine.

[45] The transportation and removal of Onondaga from the water was featured in the 'Supersize Submarine' episode of the Monster Moves documentary series.

After repairs and refurbishment, Onondaga and her attached museum, as a publicly accessible submarine, opened on 29 May 2009, with over 100,000 visitors in the first year.