The New York Times called it a “mystery,” but the United States executed a covert sea operation that was kept secret—until now The U.S. Navy’s Diving and Salvage Center can be found in a location as obscure as its name—down what was once a country lane in rural Panama City, a now-booming resort city in the southwestern panhandle of Florida, 70 miles south of the Alabama border. The center’s complex is as nondescript as its location—a drab concrete post-World War II structure that has the look of a vocational high school on the west side of Chicago. A coin-operated laundromat...