The section, which operates as the center of flight operations on a carrier, is more than 98.4 feet high, houses 110 compartments and has more than 144,000 feet of cables.
BAE said the structure has now been loaded onto a barge and will be transported to a shipyard in Rosyth, Scotland, where the 827 ton structure will be lifted and fitted onto the vessel's flight deck.
"The load out of the aft island marks a great achievement for the team here on the [River] Clyde," said Angus Holt, Queen Elizabeth Class Block Delivery director for BAE Systems. "It is a real credit to their hard work and skill that the block was completed ahead of schedule and to an exceptional standard, demonstrating the pride and drive among the team to deliver the nation's flagships."
HMS Queen Elizabeth uses an innovative design of two islands. The forward island, which holds the main bridge of the vessel, and the aft island. BAE said each is designed to take over the role of the other in an emergency.
Construction of the carrier is being conducted by BAE Systems, Thales UK, Babcock and the Ministry of Defense in a consortium called the Aircaft Carrier Alliance