Britain's nuclear deterrent rests on a Vanguard class submarine lurking in the depths of the ocean to avoid detection.
Sailors are complaining at the state of repair of their submarines
The Royal Navy has four of these submarines, each armed with 16 missiles carrying multiple nuclear warheads. At all times one boat is on patrol.
BBC Radio 4's File On 4 has heard sailors' complaints that the condition of these and the rest of the navy's submarines are being affected by government cost-cutting.
Indeed one sailor serving on a Trident submarine claims they are "just about" seaworthy, with crews scouring other subs for spare parts in a massive "make do and mend" operation.
The senior rating said crews frequently experienced problems with oxygen production equipment on board as well as with the batteries on the craft.
"Our subs are nuclear powered but if for any reason we can't use the nuclear power we would use the battery," he said.
"If it was in an escape situation, the reactor would be shut down and you would need the battery.
"There's so many things that seem to go wrong that the guys do an unbelievable job fixing it, and how they keep going is beyond me.
"If the government want a Premier League weapons platform, you need to have the equipment, the skills, you need to have all of this in place in case anything goes wrong and they don't have that.
"They want a Premier League system and they're paying Third Division prices.
He added: "The boats are safe to go to sea, but I would say just safe."
Former First Sea Lord Sir Alan West argues that cost cutting is a problem across the Navy.
Sir Alan said the service has some excellent sailors of whom the nation should be proud, but added: "What really demotivates them is that they're working flat out to make sure their system, their ship, their aeroplane is the best in the world, sorry we haven't got this spare part."
But Armed Forces Minister Adam Ingram denied there was any problem.
He said the Navy's overall morale is of the "highest standard".
And he rejected the claims that Trident submarines are just about seaworthy.
"That has never been put to me" said Mr Ingram, who added that safety on Royal Navy submarines was of the "highest order."
But sailors on the Navy's nuclear powered Trafalgar class submarines, which carry conventional weapons, are also concerned.
Former Petty Officer Paul Reidy said that towards the end of his career he was worried about the state of the submarines he served on.
The vessels suffered from leaking hatches and unfinished equipment, he said.
"The hatches were constantly leaking, they were sealing at 50 to 100 metres down when it should be three metres down.
He added: "I have seen water all over the control room floor, we're talking about half an inch over a large area. You deal with it, mop it up but it is not ideal."
Another sailor, who wished to remain anonymous, said in his five years aboard Trafalgar class vessels they experienced potential dangerous failures of electrical systems.
He said on one occasion his craft might have sunk to the bottom of the sea with its crew trapped inside following a systems failure.
"If we weren't coming up we would have been stuck there, if we were going down we would not have been able to come back up."
Hear the full story on File on 4 Tuesday 29 May 2007 2000 BST, repeated Sunday 3 June 1700 BST.