The Upholder/Victoria-class submarines, also known as the Type 2400 (due to their displacement of 2,400 tonnes), are a class of diesel-electric submarines built in the United Kingdom in the 1980s to supplement the nuclear submarines in the Submarine Service of the British Royal Navy.
The boats were originally named the Upholder class, after the most renowned vessel of the former U class. Their British service life was short, with the vessels being decommissioned in 1994. After an unsuccessful bid to transfer these submarines to the Pakistan Navy in 1993–1994, the Canadian government eventually purchased the submarines and a suite of trainers from the Royal Navy for Canadian Forces Maritime Command (renamed to Royal Canadian Navy in 2011) to replace their decommissioned Oberon-class submarines in 1998.