HMS Artful's maiden dive was part of a two-day operation known as a 'trim and incline test', which proves the submarine's safety and stability in the water. According to BAE Systems, it involved a team of 80 highly-skilled personnel, including naval architects, engineers and Royal Navy crew members.
Time-lapse footage shows the new 97m-long submarine emptying its ballast tanks and slowly submerging to a depth of 15 metres. Only its tower is still visible once the submerge operation is complete. The submarine then stays underwater for seven hours with 22 crew members on board.
From the tests, naval architects can calculate the submarine's precise weight - which is around 7,400 tonnes - and also its centre of gravity. These calculations are vital for the boat to safely dive and resurface when it is eventually deployed with the Royal Navy.
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Successful test - "a result of years of work"
"Successfully completing the trim and incline test is a significant milestone for Artful and a result of years of work by skilled engineers, naval architects and our operations team," said BAE Systems Submarines managing director Tony Johns
"Our focus is now on completing final test and commissioning activities before she leaves Barrow for sea trials next year."
The trim and incline test was also an opportunity for the crew to test Artful's advanced systems and sensors for the first time. Equipment tested included the submarine's sonar, navigation, and optical systems - its 'eyes and ears'. Artful's sophisticated sonar manufactured by Thales - called Sonar 2076 - has the processing power of 2,000 laptops.
Artful is the third vessel in the Astute-class fleet and was launched in May this year. The state-of-the-art submarine can carry torpedoes and long-range Tomahawk cruise missiles capable of hitting targets over 1,000 miles away.
Three more vessels are currently under construction at the Barrow-in-Furness site - Audacious, Anson, Agamemnon and Ajax - and a seventh submarine has been ordered.