The U-550 was found Monday by a privately funded group organized by New Jersey lawyer Joe Mazraani. It was the second trip in two years to the site by the team, some of whom had been searching for the lost U-boat for two decades.
Using side-scan sonar, the seven-man team located the wreck listing to its side in deep water about 70 miles south of Nantucket.
Sonar operator Garry Kozak said he spotted the 252-foot submarine during the second of an exhausting two days of searching. Kozak said the team asked him if they'd found it, then erupted in joy without a word from him.
"They could see it with the grin (on my face) and the look in my eyes," Kozak said.
On April 16, 1944, the U-550 torpedoed the gasoline tanker SS Pan Pennsylvania, which had lagged behind its protective convoy as it set out with 140,000 barrels of gasoline for Great Britain, according to the U.S. Coast Guard website and research by Mazraani.
The U-boat slipped under the doomed tanker to hide. But one of the tanker's three escorts, the USS Joyce, saw it on sonar and severely damaged it by dropping depth charges.
The Germans, forced to surface, manned their deck guns while another escort vessel, the USS Gandy, returned fire and rammed the U-boat. The third escort, the USS Peterson, then hit the U-boat with two more depth charges. The crew abandoned the submarine, but not before setting off explosions to scuttle it. The submarine hadn't been seen again until Monday.