But so unexpected was Sean Smyrichinsky’s find, off the western coast of Canada, that he initially thought it was a UFO.
Now the Canadian Navy has been dispatched to see if the diver’s explosive claims stack up and he really has found an arrant atomic bomb.
If proved right, Mr Smyrichinsky may have inadvertently solved one of the biggest mysteries of the Cold War -- what happened to a nuclear bomb jettisoned by a US aircraft in 1950 just before it crashed.
Mr Smyrichinsky claimed he recently went diving in a remote area close to Pitt Island, off the coast of British Columbia, using an underwater scooter.
Gorb: Any technical insights you can offer on this piece of equipment?