The Oberon class were considered an improved version of the preceding Porpoise-class submarines, with a different frame of the pressure hull[2] and constructed from a better grade of steel.

[3][4] These build differences allowed the Oberons to have a deeper diving depth at roughly 1,000 feet (300 m).

The boats carried 258 tons of oil giving them a range of 9,000 nautical miles (17,000 km; 10,000 mi) at 12 knots.

[9] 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.

[16][17] On 11 April 1962, the purchase was announced in the House of Commons of Canada by the Minister of National Defence, Douglas Harkness.

[26][27] The submarine, built at Chatham Dockyard in England, was laid down on 25 March 1965, and launched on 17 September 1966 by Monique Cadieux, the wife of the Associate Minister of Canadian National Defence.

[32] In July 1973, Okanagan collided with the Royal Fleet Auxiliary vessel Grey Rover while exercising in British waters off the coast of Scotland.

The submarine was running submerged off the mouth of the River Clyde when the tanker hit Okanagan.

[35] Okanagan underwent her SOUP refit beginning in 1984, being handed over to HMC Dockyard at Halifax, Nova Scotia on 2 April.

[36] 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 (MARCOM).

[26] 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.

The delay of the introduction of the Victoria-class submarines led to the Oberons working past their life expectancy.

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