Dolphins were proudly worn when a man fulfilled all of the requirements to become "Qualified in submarines".

The qualification certificate reads:

"Having successfully completed the rigorous professional requirements for qualification in submarines, having gained a through knowledge of submarine construction and operation, having demonstrated his reliability under stress, and  having my full confidence and trust, I hereby certify that he is
Qualified in Submarines"

The wearing of Dolphins is a longstanding naval tradition. Earning Dolphins is a significant event in submariner's career; a special high point that instills tremendous personal pride and a sense of accomplishment.

The origin of the U.S. Navy's Submarine Service Insignia dates back to 1923. On 13 June of that year, Captain Ernest J. King, USN, later to become Fleet Admiral and Chief of Naval Operations during World War II, and at that time Commander Submarine Division Three, suggested to the Secretary of the Navy, via the old Bureau of Navigation, that a distinguishing device for qualified submariners be adopted. The design chosen consisted of a bow view of a submarine proceeding on the surface, with bow planes rigged for diving, flanked by dolphins in horizontal positions with their heads resting on the upper edge of the bow planes.
The Officer Insignia was then and is now a gold plated metal pin, worn above the left breast pocket. Enlisted men wore the insignia, embroidered in silk, on the outside of the right sleeve, midway between the wrist and the elbow. In mid-1947 the embroidered device shifted from the sleeve of the enlisted man's jumper to above the left breast pocket. Subsequently, silver metal Dolphins were approved for enlisted men.
Dolphins are earned through a rigorous qualification process. Individuals must learn the location of equipment, operation of complex systems, damage control procedures and have a general knowledge of operational characteristics of their boat. Dolphin wearers qualify initially on one boat and must requalify on each boat to which they are subsequently assigned. Once Dolphins have been earned, they are awarded to the individual by the Commanding Officer in a special ceremony.