Fourth Astute-class submarine completes first dive.

The fourth Astute class submarine, Audacious, which is being built by BAE Systems for the Royal Navy, has achieved a significant milestone by completing her first ever dive.

Fourth Astute-class submarine completes first dive

The trim and basin dive took place over two days in Devonshire Dock, at the Company's site in Barrow-in-Furness last week.

The operation, which saw Audacious submerge fully under water for the first time, tested many of her on-board systems, and proved the safety and stability of the 7,400-tonne, 97 metre-long attack submarine.

Employees from BAE Systems worked alongside Audacious' crew, including its Commanding Officer, Captain Scott Bower, to complete the test.

Officially named in December 2016 and launched in April last year, Audacious is scheduled to leave Barrow for sea trials later this year.

HMS Astute, HMS Artful and HMS Ambush are already in-service with the Royal Navy. Boats 5 and 6, Anson and Agamemnon, along with a seventh, as yet unnamed, Astute-class submarine are in different stages of construction at the Barrow site.