Sea Shadow inside HMB-1 from the access deck forward. Note HMB-1's retractable spanning roof overhead. This was used during project Azorian to allow access by Glomar Explorer to load the claw (Clementine), and to remove the claw with the submarine contents while submerged under Glomar Explorer. When not under Glomar Explorer the roof hid HMB-1's contents from Soviet aircraft and satellites.
The large green mobile crane, also from Project Azorian is visible overhead. Both the retractable roof and the crane continued to be used to hide, build and maintain HMB-1's payload during the Sea Shadow era.
The deck was added during the Sea Shadow period, aft you can see a platform that contained landing lights, part of a range used by the crew of Sea Shadow to line up their entrance to HMB-1 On the wing wall you can see ladders that lead up to the top of the wing wall and to the helicopter platform. The deck also leads aft where the brow (walkway) that leads into Sea Shadow.
The construction was complicated by a tight timeline and the need for secrecy. Four manufactures made the many modules so no one of them had the complete picture of what they were building.
The timing of operations that required opening the roof was always carefully planned to avoid overflight of Soviet satellites.