The U.S.S. Emmons was a 350-foot minesweeper rushed into service at the beginning of World War II, and it became an important part of the final island-hopping push toward Imperial Japan.

But during the Battle of Okinawa on April 6, 1945, it was overmatched in a matter of minutes as its senior ship, the U.S.S. Rodman, came under huge suicidal attacks by kamikaze. The Emmons circled its sister ship, providing fire and knocking six Japanese planes out of the sky.

But there were just too many. Four missed by mere yards and five almost simultaneously whisked low through the line of fire, crashing into the bridge and the main deck, and engulfing parts of the ship in flame. The hulk was deliberately sunk by U.S. forces the following morning, so the enemy could not capture it.

The Emmons was rediscovered in 2000, when local fishermen found oil floating in the sea off Okinawa’s Motobu Peninsula.

Now, years later, a Japanese team of archaeologists have extensively mapped the wreck using advanced 3D imaging, even though the ship sits more than 40 meters deep in the Pacific Ocean.

The combined bathymetry and structure-from-motion (SfM) photogrammetry method of producing painstaking detail is outlined in the latest issue of the International Journal of Nautical Archaeology.

“The 3D SfM model recoded detailed surface conditions, such as cracks and other damage, and adhering objects and organisms,” the scientists write. “It is therefore expected that this method can be used to create 3D models superior to those generated by multibeam bathymetric DEM, providing baseline data for the long-term study and conversation of underway sites.”

Their methodology began with a survey by a multibeam echosounder, a Sonic 2022 set at an ultrasonic frequency of 400 kHz. That survey extended in a huge rectangle around the wreck, 1 km by 2 km.

For the SfM imaging, scuba divers took seven dives to capture high-resolution images using a Nikon camera in a Nauticam housing. The 3D model was created through stitching together 1,820 total images in Agisoft PhotoScan. For further accuracy, they used the model as a base map to set ground control points for GPS coordinates.

Their findings: the Emmons held four unexploded depth charges that could be dangerous, and next to it was an engine that is likely from one of the suicidal kamikaze that knocked the minesweeper out of the war.

“The hull of Emmons lay on a coral reef ridge and was bent slightly. Since it sank it has not moved much,” the researchers said.

The site could be preserved through UNESCO as an Underwater Cultural Heritage site, like other WWII wrecks. The Japanese authors compare it to the U.S.S. Arizona at Pearl Harbor in Hawaii, as relaying lessons of the past.

“U.S.S. Emmons is a war heritage site in Japan testifying to historic events: the Battle of Okinawa, a ground battle that led to a loss of 200,000 lives, and the kamikaze attack,” the scientists said. “It has been more than 70 years since the war ended, and the number of living survivors who experienced it is gradually decreasing.

“The documentation of the war through material evidence, such as research on U.S.S. Emmons, can supplement survivor accounts to be passed down for posterity,” the paper said.