Odin class submarine
The Odin class submarine or O class was a class of six submarines developed and built for the Royal Navy. They were made to replace the aging L class submarines which didn't have the endurance to perform adequately in the Pacific. O class submarines displaced 1781 tons tons while surfaced and 2,038 submerged with a crew complement of 53. They were 283ft-6in long, 29ft-10in across, and had a draft of 16ft-11in. Powered by a 4,440 hp diesel engine, and a 1,320 hp electric motor with twin screws, O class were capable of attaining 17.5 knots surfaced, and 10 knots submerged and theoretically able to dive to 500 feet, though none were formally tested beyond 300 feet. Armament consisted of eight 21in torpedo tubes (6 bow, 2 stern) and one 4in gun.
Odin class submarines:
| HMS Odin | Launched May 5, 1928 | Lost on June 14, 1940. Sunk by Italian destroyer Strale in the Gulf of Taranto. |
| HMS Olympus | Launched December 11, 1928 | Lost on May 8, 1942. Mined off of Malta. |
| HMS Orpheus | Launched February 26, 1929 | Lost on June 27, 1940. Sunk by Italian destroyer Turbine in the Mediterranean. |
| HMS Osiris | Launched May 19, 1928 | Scrapped in September 1946 in Durban. |
| HMS Oswald | Launched June 19, 1928 | Lost on August 1, 1940. Sunk by Italian destroyer Vivaldi off of Calbria. |
| HMS Otus | Launched August 31, 1928 | Scuttled in September 1946 off of Durban. |