Hughes Mining Barge
Suisun Bay Reserve Fleet.
HMB-1 was originally used in Project Jennifer, where the US raised a sunken Soviet submarine (K-129) from the ocean floor.
HMB-1 then became the floating drydock where the proof-of-concept stealthy ship Sea Shadow (IX-529) was built. Sea Shadow is currently stored inside and both vessels are available for dontation.
USSR Sub K-129: en.wikipedia.org/wiki/Soviet_submarine_K-129_(Golf_II)
Project Jennifer: en.wikipedia.org/wiki/Project_Jennifer