Researchers announced Friday the discovery of a Navy tanker that sank nearly 60 years ago after running aground on Maro Reef in the Northwestern Hawaiian Islands.

"It’s pretty exciting," said Jason Raupp, who led the the Papahanaumokuakea Marine National Monument team that found the World War II-era vessel.

At 523 feet in length, the USNS Mission San Miguel is believed to be the largest ship ever lost in the northwestern islands.

"Over the years people have searched for it. And you would expect that it wouldn’t be that hard to find. But in fact we got really lucky," Raupp said.

The T2-type tanker left Guam on Oct. 1, 1957, and was sailing for Seattle a week later in stormy weather when it smacked into Maro Reef while running at full speed.

"They hit the reef at 15 knots, going full steam. Every effort was made to try to salvage the vessel amid flooding of the hull, but there was such extensive damage," Raupp said.

After a few hours the effort was abandoned. Fortunately, the ship wasn’t filled with oil, and the Navy was able to safely evacuate the 42-member crew.

The disaster was documented by a photo that appeared in The Honolulu Advertiser. But once the ship sank below the waves, its exact location slipped away with it.

The Mission San Miguel was built in California in 1943 to support U.S. efforts during World War II. Used for delivering petroleum products around the world, the ship was awarded its share of military commendations over the years, including a National Defense Service Medal, a Korea Service Medal, a Republic of South Korea Service Medal (retroactive) and a United Nations Service Medal.

Despite the significant role tankers played in the war, few examples of these vessels exist today, officials said.

The shipwreck was discovered Aug. 3 by the monument’s heritage research team aboard the National Oceanic and Atmospheric Administration ship Hi’ialakai, which was also carrying scientists assessing reefs for fish, coral and coral health.

The ship, which made stops at atolls, reefs and islands up and down the northwestern islands during a monthlong tour, returned to Honolulu on Thursday.

Raupp said finding the Mission San Miguel was his team’s top priority during the research vessel’s visit to Maro Reef. In preparation the team pored over the available data and narrowed down a search area where the shipwreck was more likely to be found.

The mission’s chief scientist, Scott Godwin, described Maro Reef as an eroded atoll with no ring of land to protect the reef against the open ocean. The result, he said, is a lot of churned-up water and poor visibility most of the time.

But Aug. 3 saw a lessening of the tidal cycle and with no wind, leaving the water exceptionally clear, Godwin said.

"The visibility was unbelievably good," Raupp said.

And there it was: the submerged tanker, lying on its side at a depth of 80 feet.

Raupp said that when he jumped into the water and finally saw the ship, he looked over at his fellow divers.

"Their eyes were like pie plates," he said. "It was great. It was one of those ‘aha’ moments."

Raupp said considering the wave action of the area, he expected to see the ship broken up in pieces.

Instead, the stern section was largely intact, having settled in a sandy canyon between reefs, the ship’s steering wheel still attached and standing.

"It’s really a very, very exciting discovery," he said.

Although the shipwreck now functions as a thriving artificial reef and will be left where it is, Raupp said the monument’s heritage team has a lot of work ahead of it in order to bring the story of the Mission San Miguel back to life.

Monument Superintendent Athline Clark said researchers have identified more than 60 lost ships and 70 airplane wrecks across the monument, including vessels ranging from the earliest days of the whaling era to World War II and the Korean War. Only 21 sites of the wrecks have been found.

"This is the newest star," Clark said of the tanker. "But every single one of the wrecks tells a different human story about a different era.

"What’s so amazing about the maritime heritage process is that every single find links you back to another story and another whole people and another slice of history and a reminder of what has happened in our region over all of those years," she said.

A 2013 NOAA assessment of three known shipwrecks in the Pacific named the Mission San Miguel as the top threat as a possible source of oil.

But after this discovery the ship likely will no longer warrant such standing, said William Marhoffer, emergency management and preparedness adviser with the U.S. Coast Guard.