The awesome 7,400-tonne sub is 291 foot long, the same length as a football pitch, as wide as four double-decker buses and 12 storeys high.
A true titan of the deep, the 1.2-billion-pound warship will be launched at Barrow-in-Furness in Cumbria on Thursday, the Daily Mail reported.
According to the report, its nuclear-powered engine can propel her at more than 20 knots, allowing her to travel 500 miles a day. And, despite being 50 per cent bigger than the Swiftsure and Trafalgar subs she will replace, Ambush is quieter. Her propellers are said to make less noise than a baby dolphin -- making her virtually undetectable to enemy vessels, the report said.
HMS Ambush will carry 38 missiles, a mixture of Tomahawk cruise missiles, which have a range of 1,240 miles, and Spearfish heavyweight torpedoes to target other ships and submarines.
The submarine has been fitted with the most advanced sonar and radar, which are so sensitive that they can detect enemy ships from a distance of 3,000 nautical miles. It means if the submarine is in the English Channel, it would know if a ship left New York's harbour.
But naval chiefs will hope that the newly-named craft won't suffer the same catalogue of disasters that has recently befallen her sister vessel, HMS Astute. The latter's captain, Commander Andy Coles, was relieved of his duties after the submarine ran aground on a sandbank off the Isle of Skye in October.
HMS Ambush will be unveiled and officially named by Lady Anne Soar, the wife of the Royal Navy's commander-in-chief Fleet Admiral Sir Trevor Soar. After the ceremony, the sub will be wheeled from her shed and lowered into the wet dock for further outfitting and testing, the report added.