The fourth Astute-class submarine, Audacious, which is being built by BAE Systems for the Royal Navy, has completed her first ever dive at BAE's facility in Barrow, the company announced on 15 January. 

The operation, which saw Audacious submerge fully underwater 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.

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.