The Australian government has pledged AU$500,000 (US$380,000) to match private investment in an expedition to search for Royal Australian Navy World War I submarine, HMAS AE1.
AE1 was lost without a trace on September 14, 1914 while patrolling waters off then German New Guinea. The cause of the disappearance is not known.
The loss of AE1 with her entire complement of three officers and 32 sailors was the navy's first major tragedy.
The Silentworld Foundation, Australian National Maritime Museum and Fugro Survey are also supporting the Find AE1 search, which the Papua New Guinean Government is allowing in its waters.
"HMAS AE1 is one of the world's great maritime mysteries and this expedition will be one of the most comprehensive searches for the submarine," said Defence Minister Marise Payne.
"We owe it to the men of AE1, their descendants and the entire Navy community to continue to look for those who are forever on patrol."