Key Largo opens new dive site July 10, 2002 Share 1 -- KEY LARGO, Fla. -- Sunken treasure? An artificial reef was created when the 510-foot Spiegel Grove, a retired U.S. Naval transport vessel, was sunk off Key Largo. The wreck was opened to sport divers last month, and dive operators are reporting brisk business.The home page of the Florida Keys & Key West Web site has a link for Key Largo. Diving firms and other supplier information are available on the site.