Underwater video footage and pictures captured by an expedition hired by sons of the commanding officer, Lt. Cmdr. Mannert L. Abele, allowed the Navy to confirm the discovery, Rear Adm. Douglas McAneny said Thursday in a news release.
McAneny said the Navy was very grateful to the Abele family.
"We hope this announcement will help to give closure to the families of the 70 crewmen of Grunion," he said.
The Grunion was last heard from July 30, 1942. The submarine reported heavy anti-submarine activity at the entrance to Kiska, and that it had 10 torpedoes remaining forward. On the same day, the Grunion was directed to return to Dutch Harbor Naval Operating Base. The submarine was reported lost Aug. 16, 1942.
Japanese anti-submarine attack data recorded no attack in the Aleutian area at the time of the Grunion's disappearance, so the submarine's fate remained an unsolved mystery for more than 60 years, the Navy said.
Abele's sons, Bruce, Brad, and John, began working on a plan to find the sub after finding information on the Internet in 2002 that helped pinpoint USS Grunion's possible location.
In August 2006, a team of side scan sonar experts hired by the brothers located a target near Kiska almost a mile below the ocean's surface. A second expedition in August 2007 using a high definition camera on a remotely operated vehicle yielded video footage and high resolution photos of the wreckage.
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