By CBSMiami.com Team

MIAMI (CBSMiami) – Divers in the Florida Keys National Marine Sanctuary unfurled a huge American flag underwater Saturday and attached it to a historic military shipwreck to mark 20 years since 9/11.

The 30- by 40-foot flag was carried by divers about 60 feet beneath the ocean’s surface and affixed it to the kingpost of the Gen. Hoyt S. Vandenberg, the highest point of the wreck whose bottom rests in nearly 150 feet of water.

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The 523-foot-long former Army troop transporter and Navy missile-tracking ship, was scuttled some 7 miles south of Key West in 2009 to become an artificial reef.

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The installation of the flag was followed by a flyover by two Navy helicopters.

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The tribute was observed by boaters including relatives and friends of people who died in the terrorist attacks and their aftermath.

CBSMiami.com Team