Once the wreck site was protected, site managers then embarked on a policy of ‘in situ’ preservation. Retention of archaeological structures in situ is the cornerstone of the UNESCO Convention on the Protection of the Underwater Cultural Heritage 2001, and the Australasian Institute of Maritime Archaeology Inc (AIMA). It also accords with the State and Federal Government’s approach to shipwreck management.
Australia is fortunate to have all of the combatants from the events of 31 May 1942 — M24 in its battle context, and the composite midget submarine, (created from the two midget submarines, Ha-14 and Ha-21, lifted from Sydney Harbour) now on display at the Australian War Memorial in Canberra. Ha-21’s conning tower is preserved at the Naval Heritage Centre, Sydney.
There was initial public discussion about recovering the vessel, to recover the crews’ remains.
This would be an expensive and ultimately risky undertaking for the submarine. The only way to identify the individuals would be to archaeologically excavate the internal compartments in controlled laboratory conditions. By default, this would necessitate raising the submarine and bringing it onshore. The damage caused by corrosion has affected the structural integrity of the vessel, which means that it may not survive the trip to shore intact. Any lifting operation would have involved the construction of a complex underwater lifting cradle, similar to that used in the Mary Rose or USS Monitor turret recovery.
Presuming that remains were found, the vessel would then need to be conserved and publicly displayed. The cost of such a venture has been estimated at $AUS50 to $60 million.
There is also the issue of unexploded scuttling charges within the wreck and their possible volatility.
Equally important was the ethical issue of recovery if long term conservation of the craft and associated relics collections, over many decades, could not be assured or justified. With the remains of portions of Ha-14 and Ha-21 already on display in Australia, there was a limited research argument to recover the M24 for onshore analysis.
Based on the Heritage Branch’s assessment of these ethical and practical issues, family members of the crew acknowledged that recovery of human remains was not possible.