The search for Australia’s first submarine lost during World War I has ended, 103 years after the AE1 vanished in 1914 along with its 35-member crew.

The mystery of the missing sub has puzzled the Australian Navy ever since it vanished off the New Guinean island of New Britain on September 14, 1914. AE1 was the first Allied submarine lost in the war, and though the cause of its sinking remains a mystery, the navy have finally found the previously elusive sub.

“It was the first loss for the Royal Australian Navy and the first Allied submarine loss in World War I; a significant tragedy felt by our nation and our allies,” Australian Defense Minister Marise Payne said in a statement.

Previous attempts to find the vessel turned up nothing, but a search that started just last week finally bore fruit.

“An expedition to locate the submarine took place in waters off the coast of the Duke of York Island group in Papua New Guinea this week. The search vessel ‘Fugro Equator’ located an object of interest in over 300 metres of water. Upon further inspection, confirmed the object to be AE1,” Payne explained.

“Following the discovery of the submarine, a small commemorative service was held by those on-board the survey vessel to remember those officers and sailors who lost their lives 103 years ago. Efforts are being made to contact the descendants of the crew,” Payne added.

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The AE1 made final contact with an Australian ship at 2:30pm the day it disappeared, AP reports. At the time, villagers on a nearby island were left mystified by the appearance of a “monster” or “devil fish” which breached the water before disappearing.