Cod is now a National Historic Landmark, preserved as a museum ship and memorial permanently moored in Cleveland, Ohio, and is open to visitors daily from May to November.

On 30 August 1943, the American Type C1-B cargo ship SS Alcoa Patriot opened gunfire on Cod in the Caribbean Sea at 12°25′N 076°03′W / 12.417°N 76.050°W / 12.417; -76.050, about 120 nautical miles (220 km; 140 mi) north-northwest of Barranquilla, Colombia, and 330 nautical miles (610 km; 380 mi) east of the northern entrance to the Panama Canal.

Penetrating the South China Sea, she contacted few targets, and launched an attack only once, on 29 November, with unobserved results.

She sent another to the bottom on 27 February, Taisoku Maru (2,473 tons) and two days later attacked a third, only to be forced deep by a concentrated depth charging delivered by a Japanese escort ship.

In November she took up a lifeguard station off Luzon, ready to rescue carrier pilots carrying out the series of air strikes on Japanese bases which paved the way for the Battle of Leyte later that month.

On 24 March she sailed from Pearl Harbor for the East China Sea on her sixth war patrol.

QM2c Lawrence E. Foley and S1c Andrew G. Johnson were washed overboard while freeing the torpedo room hatch.

[10] After refitting at Guam between 29 May and 26 June 1945, Cod put out for the Gulf of Siam and the coast of Indo-China on her seventh war patrol.

Naval Base Subic Bay, between 21 July and 1 August Cod made 20 gunfire attacks on the junks, motor sampans, and barges which were all that remained to supply the Japanese at Singapore.

After inspecting each contact to rescue civilian crew, Cod sank it by gunfire and torpedoes, sending to the bottom a total of 23.

On 1 August, an enemy plane strafed Cod, forcing her to dive, leaving one of her boarding parties behind.

All seven of her war patrols were considered successful and Cod was awarded seven battle stars for her service in World War II, Cod's battleflag and conning tower both carry a cocktail glass above the name O-19 to commemorate the rescue and the party.

Today, Cod is the only World War II United States Navy museum submarine that has not had stairways and doors cut into her pressure hull for public access[12] and is the only World War II Fleet submarine that is still intact and in her wartime configuration.

The ship's 5-inch deck gun, Mark IV Torpedo Data Computer, SJ-5 radar, Sound-powered telephone, and all five diesel engines have been restored and are fully operable.

Cod acquired two General Motors Cleveland Model 16-248 V16 diesel engines that had originally been used aboard another World War II submarine, USS Stingray (SS-186).

[19] Cod was used for exterior and interior scenes for the Smithsonian Channel war documentary Hell Below to depict USS Tang, U-99 and U-100.

[21] Cod was used for exterior and interior scenes for the Dolph Lundgren motion picture Operation Seawolf to depict World War II German U-Boats.