On January 20, 1942, Japanese Navy submarine I-124 found its final resting place 53 metres below the waves of the Beagle Gulf, north-west of Darwin.
It was struck by depth charges deployed by the Royal Australian Navy as the two sides competed for control of waters to Australia's north during World War II.
For the 80 crew members aboard I-124 at the time, there was no hope of escape.
The remains of I-124 now constitute a war grave, and is a site still of deep significance to family members and the Japanese government. In 2018, the country's former prime minister Shinzo Abe visited Darwin to pay tribute.
But despite its historical and cultural significance, it isn't easy to reach.
"This has just been in the too hard basket for quite a long time, but it's so significant at the same time. So it's been a real conflict," Northern Territory senior heritage officer and maritime archaeologist Dr David Steinberg said.
The Top End's strong tides, murky waters and the submarine's depth have made it tricky to access.
"It's deep, it's remote, it's difficult to get to."
Dr Steinberg's team of archaeologists and experienced divers has, after three years of work, just completed an Australian first by using specialised cameras mounted to underwater scooters to create a 3D model of the vessel.
Modelling could solve long-standing questions
Out of respect, researchers practised "non-disturbance" by only mapping the outside of the I-124.
At the very least, the model will provide an important educational tool and comfort for relatives of the submariners who perished.
"We can take that data, that 3D model and present that to the NT public, the Australian public, who so few of them will ever be able to dive that shipwreck," research director for the Major Projects Foundation, Matthew Carter, said.
"While you can't dive it, you can have it on your desktop, you can look at it on your phone."
But even more importantly, with return visits from crews of divers, researchers hope to understand how quickly the site is deteriorating, and whether there are ways to preserve the war grave.
"That involves bringing maritime archaeologists and technical divers back on a relatively regular basis to make sure the site is conserved, that it's not being damaged, that there's no human disturbance or impacts," Dr Steinberg said.
"It's not an adventure dive, this is a scientific project to record that site, collect very important baseline data so we can manage the site [and] protect it in conjunction with the Japanese."
There's also interest in understanding the I-124 submarine's unique quirks. While four I-121-class submarines were manufactured with the purpose of laying undersea mines, three were destroyed before the Japanese surrender in 1945.
"We know very little about the submarine. We have some ship plans [but] there's some conflict about how this was built, how it was modified over the war," Dr Steinberg said.
"Those are research questions we can ask."
Symbol of strengthening ties
Only weeks after the I-124 was sunk, 236 people were killed during the Bombing of Darwin.
Both countries clashed ferociously throughout the Pacific campaign, and it was difficult to imagine how the relationship between Australia and Japan could ever possibly recover.
But 80 years on, the two countries have worked collaboratively to remember the 80 submariners who died aboard I-124.
The project to map the I-124's exterior was undertaken by the NT government's heritage branch and was funded by the federal government, with in-kind support from the pearling company Paspaley.
Takenobu Hamaguchi from the Australian-Japanese Association of the Northern Territory said he hoped the project would provide closure to the families of those aboard the vessel.
He said sand retrieved from the wreckage would be sent back to loved ones in Japan, with an eye towards one day repatriating the bodies of those on I-124.
"It will be a hard task — we understand it's a difficult thing but sure, if it can be done."
