AUSTRALIA’S most enduring military mystery has been solved after the wreckage of the country’s first submarine was found more than a century after it vanished off Papua New Guinea, officials said Thursday.

HMAS AE1, the first of two E Class submarines built for the Royal Australian Navy, disappeared on Sept. 14, 1914 near the Duke of York Islands with 35 crew members from Australia, Britain and New Zealand on board.

It was the first Allied submarine loss in World War I.

AE1 was found in more than 300 meters of water after an expedition — the 13th such search — was launched last week using Fugro Equator, a ship also used by Australia to hunt for missing Malaysia Airlines flight MH370.

“After 103 years, Australia’s oldest naval mystery has been solved,” Defense Minister Marise Payne told reporters in Sydney.

Payne said she hoped the discovery would help investigators establish the cause of the sinking. Rear Admiral Peter Briggs said the most likely cause of the loss “remains a diving accident.”

“The submarine appears to have struck the bottom with sufficient force to dislodge the fin from its footing,” Briggs said.

He said the vessel appeared to have suffered a “post sinking, high energy event” that would have caused the submarine to flood rapidly, probably near the surface. A newspaper pointed to a possible torpedo explosion or the rupture of a high-pressure air cylinder.   (SD-Agencies)