Building a classified warship requires more than secrecy clearances and locked doors. It requires hiding the ship itself. Lockheed solved this problem at their Redwood City, California, facility by constructing the Sea Shadow inside the Hughes Mining Barge, known as HMB-1, which served as both floating dry dock and perfect concealment. At 324 feet long, the barge could swallow the 164-foot Sea Shadow completely and seal shut. Workers entered through the barge to reach the ship. When testing demanded open water, the barge's doors opened after sunset and the angular vessel slid out into the bay. By dawn, it was back inside, the barge doors sealed, and nothing on the surface suggested anything unusual had happened. This arrangement continued from 1985 to 1993, years during which the Sea Shadow accumulated thousands of miles of nighttime testing without public detection.

The Sea Shadow looked like nothing else afloat. Its hull used a SWATH design -- small-waterplane-area twin hull -- meaning two torpedo-shaped pontoons sat fully submerged beneath the waterline, connected to the superstructure by angled struts. Above the water, the ship was all flat panels and sharp angles, every surface canted to deflect radar energy away from its source rather than bouncing it back. The effect was a vessel with the radar signature of a small fishing boat despite displacing 560 tons. The SWATH design served a dual purpose: those submerged hulls gave the ship remarkable stability in rough seas, handling conditions up to sea state 6, with waves reaching 18 feet. Observers compared the angular superstructure to the casemate of a Civil War ironclad ram, an apt comparison given that both designs prioritized deflection over aesthetics.

In 1993, the Cold War over and the technology proven, the Navy unveiled the Sea Shadow to the public. The angular black vessel generated immediate fascination. Here was a ship that had been operating in San Francisco Bay for eight years without anyone noticing, built by the same company and inside the same barge connected to one of the CIA's most audacious Cold War operations. The Sea Shadow's stealth principles influenced the design of the DDG-1000 Zumwalt-class destroyer, whose tumblehome hull and angular superstructure echo the lessons learned from those nighttime runs on the bay. The ship also tested automation technologies aimed at reducing crew requirements, operating with a complement of just 12 people -- a fraction of what conventional warships demand.

After decommissioning, the Sea Shadow entered an unlikely limbo. The Navy transferred it to the Suisun Bay Reserve Fleet, where it sat alongside mothballed World War II cargo ships and Cold War-era transports. Multiple museums expressed interest, but none could meet the financial requirements of maintaining and displaying the vessel and HMB-1 together. The Navy stipulated they could not be separated. By 2006, when no suitable museum partner materialized, the government listed the pair for disposal. The initial offering attracted no bidders. Eventually, both the Sea Shadow and HMB-1 were listed for dismantling sale. In 2012, Bay Ship and Yacht Company of Alameda, California, purchased them. The ship that radar could not find was cut apart for scrap metal, its angular panels reduced to ingots. It lived as a secret, served as an experiment, inspired the fiction of a James Bond villain's stealth ship in Tomorrow Never Dies, and died as recycled steel.