Continuously at sea: HMS Vengeance passes seven-month mark on deployment

One of the Royal Navy's submarines has hit a new milestone on her deployment, as she has now thought to have been at sea for seven months.

HMS Vengeance, a Vanguard-class nuclear submarine, departed for her deployment on 12 April this year. 

Vengeance's deployment likely breaks the previous record of 205 days, set by another Vanguard-class submarine earlier in 2026.

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However, this has not been confirmed, given the Ministry of Defence's policy of not confirming details about the length and nature of submarine deployments. 

The vessel's role is to carry the Trident ballistic missile system. 

She completed a three-and-a-half-year refit in 2015 to refuel her reactor and improve her electronics and machinery, according to the Royal Navy. 

The Royal Navy has at least one nuclear-armed submarine patrolling the seas as part of the UK's nuclear deterrent. 

The Navy has four submarines capable of being armed with Trident – HMS Vanguard, HMS Vengeance, HMS Victorious and HMS Vigilant – which together make up the Vanguard-class. 

Their mission forms part of the Continuous at Sea Deterrent (CASD), which has been operational since 1969. 

Under the CASD, at least one nuclear-armed ballistic missile submarine remains on patrol at sea, undetected, at all times. 

It aims to preserve peace, prevent coercion and deter aggression for both Britain and Nato, at a time of increased threats from the likes of Russia. 

The fleet will soon be replaced by a new generation of submarines, the Dreadnought-class, which is expected to enter service in the early 2030s.