A remarkable naval experiment came to light after the war was over, deemed so unlikely that when The Illustrated London News first heard of it, they believed it to be a hoax. The suggestion that attempts were made to train sea lions were trained to hunt submarines, did seem far-fetched. However, after a thorough investigation, they were satisfied with its authenticity enough to publish a lavish spread on it in April 1919. ?In the summer of 1917 the Admiralty hit on a novel way of hunting submarines. It was simply to employ tame sea-lions (Otaria Gillespie) to track them down-the idea being that the sea-lion could be taught to distinguish the noise of a submarine?s propeller and to follow it in the hope of getting food. A buoy would be attached to the animal, and a trawler would follow the buoy and drop a depth charge when the sea-lion appeared to have found the submarine.? Here is Billy the submarine hunting sea lion, being fed by his keeper through a trap door in his muzzle.