A United Kingdom nuclear-warhead armed ballistic missile carrying submarine narrowly escaped disaster as it sunk to perilous depths due to a malfunctioning gauge, reported a British publication, The Sun.

The incident involved a Vanguard-class submarine (SSBN), operating in the Atlantic Ocean with approximately 140 crew members and nuclear- warhead armed Trident ballistic missiles on board.

As the submarine prepared to embark on patrol, a malfunction in its depth gauge led the crew to believe it was at a level, when, in reality, it was still diving, The Sun report said.

The submarine was on the verge of entering the critical "danger zone" of depth that it could withstand, narrowly avoiding a potential disaster, according to the publication.

Nevertheless, engineers identified a second gauge, prompting them to raise the alarm.

A source quoted by The Sun stated, "It's not the engineers' job to control the sub's depth, but they saw how deep they were and realised something was wrong."

"Technically, the sub was still at a depth where we know it can operate, but if it ever has to go that deep, the whole crew is piped to action-stations. That hadn't happened. The sub wasn't supposed to be there, and it was still diving. And if it had carried on going, it doesn't really bear thinking about," the source stated.

Since 1969, a submarine armed with nuclear weapons has consistently been on patrol, serving as a continuous deterrent for the UK.

The Royal Navy currently oversees four Vanguard-class submarines, each taking turns to fulfil this crucial role. However, these aging vessels are slated for replacement with the new Dreadnought class submarines in the 2030s.

A spokesperson for the Royal Navy remarked, "our submarines continue to meet their commitments, deploying globally on operations, protecting national interests, and keeping us and our allies safe. While we do not comment on specific details regarding submarine operations, safety of our personnel is always the highest priority."