The Oberon class was a 27-boat class of British-built diesel-electric submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s based on the successful British Porpoise-class

British Porpoise class submarine

The Porpoise class was an eight-boat class of diesel-electric submarines operated by the Royal Navy. This class was originally designated patrol submarines, then attack. They were the first conventional British submarines to be built after the end of World War II...

 submarine.

Thirteen were constructed for the Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

, while another fourteen were built and exported to other countries' navies: six to the Royal Australian Navy

Royal Australian Navy

The Royal Australian Navy is the naval branch of the Australian Defence Force. Following the Federation of Australia in 1901, the ships and resources of the separate colonial navies were integrated into a national force: the Commonwealth Naval Forces...

, three to the Royal Canadian Navy

Royal Canadian Navy

The history of the Royal Canadian Navy goes back to 1910, when the naval force was created as the Naval Service of Canada and renamed a year later by King George V. The Royal Canadian Navy is one of the three environmental commands of the Canadian Forces...

 with an additional two British submarines later transferred, three to the Brazilian Navy

Brazilian Navy

The Brazilian Navy is a branch of the Brazilian Armed Forces responsible for conducting naval operations. It is the largest navy in Latin America...

, and two to the Chilean Navy

Chilean Navy

-Independence Wars of Chile and Peru :The Chilean Navy dates back to 1817. A year before, following the Battle of Chacabuco, General Bernardo O'Higgins prophetically declared "this victory and another hundred shall be of no significance if we do not gain control of the sea".This led to the...

.

As of 2006, at least fourteen Oberons are confirmed to have survived in some form: Seven as museum boats or tourist attractions, two preserved in partial form as monuments, while five are to be converted into museum boats, or are otherwise awaiting disposal.
The Oberon class was based heavily on the preceding Porpoise class

British Porpoise class submarine

The Porpoise class was an eight-boat class of diesel-electric submarines operated by the Royal Navy. This class was originally designated patrol submarines, then attack. They were the first conventional British submarines to be built after the end of World War II...

 of submarines, which were in service from 1956 to 1988.