Scientists discovered a World War II era Japanese submarine off the Hawaii Coast while plumbing the Pacific Ocean, Reuters reported.

Scientists at the University of Hawaii at Manou told Reuters the I-400 was found in August off the southwest coast of Oahu. The 400-foot "Sen-Toku" class vessel ship was preparing to attack the Panama Canal before being scuttled by U.S. forces. The vessel went missing in 1946.

"The I-400 has been on our 'to-find' list for some time. It was the first of its kind of only three built, so it is a unique and very historic submarine," Terry Kerby, who led the team who discovered the vessel, said in a statement. "Finding it where we did was totally unexpected. All our research pointed to it being further out to sea.

"The multi-beam anomalies that appear on a bottom survey chart can be anything from wrecks to rocks-you don't know until you go there. Jim and Hans and I knew we were approaching what looked like a large wreck on our sonar. It was a thrill when the view of a giant submarine appeared out of the darkness."

The discovery resolves a decades-old Cold War mystery of just where the lost submarine lay, and recalls a different era as one war ended and a new, undeclared conflict emerged, according to a press release.

I-400 was one of the five Japanese submarines captured by the U.S. Navy at the end of World War II.

"It was torpedoed, partially collapsed and had sunk at a steep angle," Dr. Delgado, an archaeologist with the National Oceanic and Atmospheric Administration (NOAA) which helped to fund the dive, told Reuters.

At the time, the I-400 was the largest submarine ever built until the introduction of nuclear-powered subs in the 1960s.

The discovery of the submarine was part of a series of dives funded by a grant from the NOAA Office of Exploration and Research and the University of Manoa's School of Ocean and Earth Science and Technology (SOEST).

Scientists were searching for submarines and other submerged cultural resources as part of the NOAA maritime heritage research effort.

I-400's sister ship, the I-401, was discovered off the coast of Oahu in 2005.

"These historic properties in the Hawaiian Islands recall the critical events and sacrifices of World War II in the Pacific, a period which greatly affected both Japan and the United States and shaped the Pacific region as we now know it," Van Tilburg, maritime heritage coordinator for NOAA in the Pacific Islands region, said in a statement. "Our ability to interpret these unique weapons of the past and jointly understand our shared history is a mark of our progress from animosity to reconciliation.

"That is the most important lesson that the site of the I-400 can provide today," Tilburg said.