The Sea Shadow is an experimental stealth ship built for the Navy in 1985 by the Lockheed Corporation for $50 million. She was built inside the Hughes Mining Barge which acted as a floating dry dock (and was eventually involved with Project Azorian, recovering a Soviet submarine from the ocean floor.)
Her purpose was to test naval vessel stealth technology to determine if radar-evading technology in aircraft was also possible in water. The experiment was a success, and used in secret for years until being exposed to the public until 1993, but the vessel was never reproduced.
In 2006, the Sea Shadow and the Hughes Mining Barge were relocated to Suisun Bay and placed in the Mothball Fleet where they have been moored since.
Yesterday, news broke that a Bay Area company purchased the Hughes Mining Barge at auction. They will preserve the barge and use it as a floating dry dock, however, the auction required the purchaser to destroy the Sea Shadow.