HMS Trenchant has been away for 335 days taking part in operations to tackle terrorism and the global drugs trade. Seven of its 170 crew remained on board the Trafalgar-class sub for its entire deployment, spending 4,700 hours – six and a half months – underwater.
The mammoth deployment, taking in Bahrain, Jordan, Crete and Gibraltar, spanned 38,800 nautical miles, enough to circle the planet one and three quarter times.
Jubilant families lined the seafront in Plymouth, Devon, to greet the homecoming seamen as the 5,000-tonne vessel headed into the city's Devonport naval base.
Commander Irvine Lindsay, HMS Trenchant's commanding officer, said: "It is believed that this 11-month period away from the UK is the longest ever UK nuclear submarine deployment.
"The ship's company have met every challenge head-on."
HMS Trenchant, launched in 1986, is due to be decommissioned in 2017.
In 2007 it the became the first Royal Navy vessel to fire the new Block IV Tomahawk cruise missile in a live-firing trial in the Gulf of Mexico.
The long-serving sub was involved in a notorious maritime accident in 1990 when it snagged a trawler in the Bute Sound in Scotland, drowning its four-man crew.
Yesterday, the cheers rang out as HMS Trenchant finally arrived home, as parents, spouses and children waved wildly. Pamela Tarr, 64, was there to welcome Chris Parr, 37, a leading hand who served the entire 11 months at sea.
She said: "I just can't believe how long he's been away and it is amazing to finally have him home with us.
"We are ecstatic and the proudest parents in the world".