How Many Submarines Does the UK Have? Astute, Vanguard and AUKUS
The Royal Navy has nine submarines in service, all nuclear-powered: four Vanguard-class boats that carry the Trident deterrent and five Astute-class attack submarines. It has had no conventional submarines since 1994. A sixth Astute boat, HMS Agamemnon, was commissioned in September 2025 and is completing its trials, and a seventh is being built at Barrow-in-Furness. Under the AUKUS pact with Australia and the United States, Britain plans up to 12 new attack submarines from the late 2030s.
This guide counts the fleet, explains what each class does and sets out the plans for the next generation.
How many submarines does the UK have?
The Ministry of Defence counted nine submarines in its statistics for 1 April 2026: four ballistic missile boats and five attack boats.
| Class | Type | In service | Building or planned | Main role |
|---|---|---|---|---|
| Vanguard | Ballistic missile submarine | 4 | Replaced by 4 Dreadnought boats from the early 2030s | Nuclear deterrence |
| Astute | Attack submarine | 5 | Agamemnon completing trials; Achilles building | Hunting submarines and ships; land attack |
| Dreadnought | Ballistic missile submarine | 0 | 4 under construction | Nuclear deterrence |
| SSN-AUKUS | Attack submarine | 0 | Up to 12 planned | Replacing Astute |
The four Vanguard boats and the Trident system they carry are described in our guide to British nuclear weapons. The rest of this guide is about the attack submarines.
The Astute class
The Astute class is the Royal Navy’s current attack submarine, built by BAE Systems at Barrow-in-Furness with reactors from Rolls-Royce. The first, HMS Astute, entered service in 2010 after years of delay. Its reactor is designed to last the life of the boat without refuelling, and the boat makes its own oxygen and fresh water, so the length of a patrol is limited by the food it carries.
| Item | Figure |
|---|---|
| Displacement | About 7,400 tonnes submerged |
| Length | 97 m |
| Speed | Over 30 knots submerged |
| Crew | About 98 |
| Torpedo tubes | 6 × 533 mm |
| Weapons | Up to 38 Spearfish torpedoes and Tomahawk cruise missiles |
| Reactor | Rolls-Royce PWR2, no refuelling for the life of the boat |
| Programme cost | About £12.2 billion for seven boats |
Its sonar is regarded as among the best in service anywhere, and the class is considered one of the quietest submarines afloat. A comparison with the French equivalent is in our article on Astute and Suffren.
The seven boats
Astute, Ambush, Artful, Audacious and Anson are in service. HMS Agamemnon, the sixth, was commissioned in September 2025 but was still finishing its in-water commissioning a year later, and the Ministry of Defence declines to give its in-service date. The seventh, Achilles, is at an advanced stage of construction at Barrow; its progress was set back by a fire in the building hall. Even with all seven in service, the attack submarine force will be far smaller than the dozen or more boats the navy had at the end of the Cold War.
What do British attack submarines do?
Their first task is to protect the Vanguard boats as they leave and return to Faslane on the Clyde, making sure no foreign submarine is following. The second is to hunt Russian submarines in the North Atlantic and the gap between Greenland, Iceland and the UK. They also escort the aircraft carriers, gather intelligence and can fire Tomahawk missiles at targets on land, as HMS Triumph did over Libya in 2011. Their weapons are described in our guide to British missiles.
Availability is the weakness. Docks at Faslane and Devonport have needed repairs, maintenance has run late, and there were reports in 2024 and 2025 that at times only one or two attack submarines were ready for sea. Patrols by the boats that are available have grown longer to compensate.
SSN-AUKUS: the next submarine
In 2021 Britain, Australia and the United States agreed the AUKUS partnership, under which Australia will acquire nuclear-powered submarines. The design chosen is British: SSN-AUKUS, a larger boat than Astute that will use American weapons and combat systems. Britain will build its own at Barrow, and Australia will build its boats at Adelaide after first buying American Virginia-class submarines.
The Strategic Defence Review of June 2025 set a goal of up to 12 SSN-AUKUS boats for the Royal Navy, delivered from the late 2030s at a rate of one every 18 months. More than £4 billion in contracts has already gone to BAE Systems, Rolls-Royce and Babcock. Barrow’s workforce, which fell from 13,000 to 3,000 after the Cold War, is about 10,000 and is planned to reach 17,000.
Frequently asked questions
How many submarines does the UK have?
Nine in service on 1 April 2026: four Vanguard-class ballistic missile submarines and five Astute-class attack submarines. All are nuclear-powered.
Does the UK have diesel submarines?
No. The Royal Navy retired its last conventional submarines in 1994 and has operated only nuclear-powered boats since.
How many Astute-class submarines are there?
Seven are planned. Five are in service, HMS Agamemnon is completing trials and HMS Achilles is under construction.
What weapons do Astute submarines carry?
Up to 38 Spearfish heavyweight torpedoes and Tomahawk land-attack cruise missiles, fired from six torpedo tubes.
What is SSN-AUKUS?
A new British-designed nuclear attack submarine to be built for both the Royal Navy and Australia. Britain plans up to 12 from the late 2030s.
Where are UK submarines based?
At HM Naval Base Clyde, at Faslane in Scotland. All Royal Navy submarines are planned to be based there.
- UK Ministry of Defence – UK armed forces equipment and formations 2026: gov.uk
- UK Defence Journal – HMS Agamemnon remains in final in-water commissioning (September 2026): ukdefencejournal.org.uk
- Calibre Defence – SDR: UK sets goal of 12 SSN-AUKUS boats from late 2030s (June 2025): calibredefence.co.uk
- Naval Technology – Astute-class attack submarines: naval-technology.com
