(Newser) – The ocean floor off Massachusetts' Nantucket Island has finally yielded a 70-year-old secret: the location of a sunken German sub from World War II. The U-550, which had wreaked havoc along the East Coast, went down in April 1944 in a battle with US ships, but researchers had been unable to find it until now, reports the Boston Globe. The sub is largely intact, and the divers who located it this week via sonar plan to return soon to further document the site.

“They’ve looked for it for over 20 years,” Joe Mazraani, a New Jersey diver, tells the Globe. "It's another World War II mystery solved.” (Read more Germany stories.)

