HMS Audacious is under construction at BAE Systems
A naval ceremony is taking place to mark the start of work on the latest submarine under construction at a Cumbrian shipyard.
Nuclear-powered HMS Audacious will be the fourth Astute-class vessel to be built at BAE Systems in Barrow.
Local MP and Secretary of State for Defence, John Hutton, will perform the keel-laying ceremony on Tuesday.
The keel is a large beam around which the hull is built - the first part of the vessel to be constructed.
Shipyard managing director, John Hudson, said: "This is a hugely important day for us - keel-laying is very traditional and recognises the perils of the sea.
"The ceremony basically wishes the crew and vessel good fortune as it goes into service."
Astute class submarines will eventually replace the Swiftsure and Trafalgar class vessels, which have been in service since the 1970s and 1980s.
They can circumnavigate the globe without needing to surface as they make their own air and water.
Accurate weapons systems mean that if positioned in the English Channel, their cruise missiles could pinpoint targets as far away as North Africa.