Oberon-class Patrol Submarine

The Oberon-class submarine was a ship class of twenty-seven British-designed submarines operated by five different nations. They were designed as a direct follow-on from the Porpoise-class: physical dimensions were the same, but stronger materials were used in hull construction, and updated equipment was fitted.

The submarines were built between 1957 and 1978 by four shipyards: Cammel Laird (4), Chatham Dockyard (6), Scotts Shipbuilding and Engineering Company (11) and Vickers-Armstrongs (6). Thirteen of the submarines were operated by the Royal Navy, six by the Royal Australian Navy, three by the Brazilian Navy, three by the Royal Canadian Navy/Canadian Forces Maritime Command (plus two ex-Royal Navy boats later acquired for non-commissioned roles), and two by the Chilean Navy.

The Oberons operated during the height of the Cold War, with duties including surveillance, tracking of other ships and submarines, delivery and retrieval of special forces personnel, and serving as targets for anti-submarine training. Submarines of the class were in service until 2000. As of 2015, twelve of the submarines are preserved intact as museum vessels, another three are partially preserved (with some exterior portions of the submarine on display), and one is in private ownership and awaiting conversion for display. The rest have been sold for scrap.

Royal Navy

 * HMS Oberon (S09)
 * HMS Odin (S10)
 * HMS Orpheus (S11)
 * HMS Olympus (S12) - transferred to Canada as a stationary training vessel at Halifax, Nova Scotia, scrapped in 2011
 * HMS Osiris (S13) - transferred to Canada as a parts hulk
 * HMS Onslaught (S14)
 * HMS Otter (S15)
 * HMS Oracle (S16)
 * HMS Ocelet (S17) - museum ship
 * HMS Otus (S18) - museum ship
 * HMS Opossum (S19)
 * HMS Opportune (S20)
 * HMS Onyx (S21) - museum ship

Royal Australian Navy

 * HMAS Oxley (S57)
 * HMAS Otway (S59) - museum ship
 * HMAS Onslow (S60) - museum ship
 * HMAS Orion (S61)
 * HMAS Otama (S62) - museum ship
 * HMAS Ovens (S70) - museum ship

Royal Canadian Navy

 * HMCS Ojibwa (S 72) - museum ship
 * HMCS Onondaga (S 73) - museum ship
 * HMCS Okanagan (S 74) - museum ship

Brazilian Navy

 * NRB Humaitá (S20)
 * NRB Tonelero (S21)
 * NRB Riachuelo (S22) - museum ship

Chilean Navy

 * BAC O'Brien (S22) - museum ship
 * BAC Hyatt (S23)