The Capitan O'Brien class were three submarines built for the Chilean Navy in the late 1920s.

The lead boat, Capitan O'Brien, was launched on 2 October 1928 and the other two on 15 January 1929.

[1] The Odin class was the Royal Navy's leading submarine design in the post-World War I era, equipped with strengthened pressure hulls and fuel carried in the ballast tanks to improve rapid diving.

[1] The submarines were propelled by two shafts powered by two Vickers diesel engines creating 2,750 brake horsepower (2,050 kW) while surfaced and two electric motors creating 1,300 hp (970 kW) while submerged.

The submarines were also armed with eight 21 in (533 mm) torpedo tubes, with six located in the bow and two in the stern.