Australia's first submarine, which sank along with 35 crew members in the early days of World War I, has been found off the coast of Papau New Guinea.

The wreck of the submarine HMAS AE1 is the country's oldest, and one of its most significant, military mysteries, Australia's Department of Defence said in a statement Thursday.

The AE1 became the first Allied loss in WW1 when on Sept. 14, 1914, it vanished off the coast of Rabaul, a town in the northeast part of Papau New Guinea. The loss of the AE1 also was the first for the Royal Australian Navy.

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Last week, more than 103 years after the AE1 disappeared, a search vessel named the Furgro Equator launched the latest search for the submarine. The sunken AE1 was discovered in about 300 meters of water near the Duke of York Islands, east of Rabaul.

The Furgro Equator crew held a small ceremony after finding the submarine.

The find was applauded by Australia's Minister for Defence Marise Payne and Australian War Memorial Director Dr. Brendan Nelson.

“Now we can properly mourn the deaths of those men who served in AE1, and commemorate their sacrifice in a meaningful and fitting way," Nelson said in a statement. "I know that the descendants of the crew will feel comfort in knowing the final resting place of their family members is now known and will be protected.”

Efforts will now begin to find descendants of those killed in the AE1 wreck.

The Australian National Maritime Museum will use the research to determine what happened to the AE1.

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