A Dec. 7, 1941, mystery is now in better focus, with new imagery of a PBY Catalina “flying boat” sunk off the Marine Corps base during the Japanese attack.

The National Oceanic and Atmospheric Administration released photos and video Thursday of the PBY-5, which rests in three large pieces in 30 feet of murky water between the base hangars and Coconut Island in Kaneohe Bay.

In 1994 a University of Hawaii dive team was unable to get good pictures of the wreck, and a 2008 effort by sport diving group Hawaii Underwater Explorers had limited success, NOAA said.

The new imagery is from a June exploration by students from UH’s Marine Option Program that was coordinated by Hans Van Tilburg, a maritime archaeologist with NOAA’s Office of National Marine Sanctuaries.

“We had a couple opportunities where we had much better visibility, and we have better cameras now with wide-angle lenses — so we’re able to get closer and get some good pictures and video,” Van Tilburg said.

The site visit showed the mooring cable was still attached to the plane, leading to the theory that it was one of four to six of the PBYs in the bay that were among the 36 aircraft assigned to the base at the time of the attack.

“The fuel tanks are in the midsection of the wing, and the wing is up above the fuselage on these big PBYs,” Van Tilburg said. “And it really looked to us like that had been strafed and exploded.”

The throttle position suggested the port engine was being started, but the mooring cable was still on, so the crew “might have been just starting to start this thing up and they hadn’t even unhooked it from the cable yet,” he said.

The precise identity of the plane is unknown, but it is possible the crew died while attempting to take off in the face of the attack, NOAA said. Van Tilburg said bodies washed ashore the next day.

“We know that this was either part of Patrol Squadron 12 or 14, but we don’t know exactly which plane it was. And we know other planes were moored there as well,” he said.

According to a state historical account, two waves of Japanese Imperial Navy aircraft bombed and strafed Kaneohe Naval Air Station before Pearl Harbor was hit. Of the 36 PBYs based there, 27 of 33 on the ground or moored in the bay were destroyed. Three planes on patrol were damaged in air-to-air combat.

The plane wreck is protected by the Sunken Military Craft Act of 2004, which prohibits unauthorized disturbance. It’s also near the Marine Corps base and is not publicly accessible, Van Tilburg said.

He said NOAA’s recommendation to the base is that the plane wreck be added to an already existing National Landmark listing.

“The new images and site plan help tell the story of a largely forgotten casualty of the attack,” Van Tilburg said. “The sunken PBY plane is a very important reminder of the ‘Day of Infamy,’ just like the USS Arizona and USS Utah. They are all direct casualties of Dec. 7.”

Van Tilburg raised the possibility that other PBYs sunk Dec. 7 might still be out there. The new imagery can be found at sanctuaries.noaa.gov/shipwrecks/pby-5.

The waters around the Marine Corps base and old Bellows Field hide a number of plane wrecks. Three teens spearfishing in Kailua Bay in 1977 came across a P-40 Warhawk fighter and retrieved a .50-caliber machine gun, two .30-caliber guns, a control stick, a clock, a gauge and ammunition.

The remnants of a P-47 Thunderbolt lie in shallow water off Bellows.

“You’d expect that,” Van Tilburg said. Anytime there’s an old runway, “things happen during training and during normal operations. There are a lot of aircraft out there. Some have been found, and a lot more haven’t been found yet.”