The 500 pound World War Two device was picked up during dredging work.
HMS Protector Returns To Portsmouth
Royal Navy ice patrol ship HMS Protector returns home to Portsmouth today (Wednesday June 27) from her maiden deployment to Antarctica.
The Royal Navy's ice patrol ship, HMS Protector, returned to port today after a seven-month maiden deployment patrolling Antarctica.
The ice-breaking ship took over the role left vacant after HMS Endurance, known as Red Plum, was left crippled following a major flood off Chile in 2008.
HMS Protector returned to Portsmouth Naval Base to be greeted by family and friends of the crew.
During the trip, the warship conducted charting and imaging of the Antarctic region for the UK Hydrographic Office, which provides 80% of the world's nautical charts.
It also assisted with the resupply of British Antarctic Survey stations.
The trip was not without incident. In February, sailors from the ship tackled a ferocious fire at a Brazilian research base on King George Island in the South Shetland Islands.
They fought for hours to tackle the blaze which killed two of the base's personnel.
HMS Protector's commanding officer, Captain Peter Sparkes, said: "Protector's return from her inaugural deployment to Antarctica represents a significant achievement for the ship's company who have transformed this unique ship into a Royal Navy warship, deployed her and operated her in the most challenging environment, and recovered her safely to the United Kingdom all within 12 months.
"We now prepare ourselves to redeploy the ship south again in September."
The 5,000-tonne ship, formerly known as MV Polarbjorn, has been leased from Norwegian company GC Rieber Shipping for three years.
The Navy has previously said it will fulfil the ice patrol ship role in the Antarctic while the future of HMS Endurance is considered.
HMS Endurance was inundated with water from a broken valve while off the coast of Chile in December 2008.
The ship was taken to the Falkland Islands before it was brought back 'piggy-back' style - on the back of the heavy lift vessel MV Target - to Portsmouth.
The Ministry of Defence later released a report from a service inquiry which found that the flooding was caused by mistakes in servicing a strainer in the engine room.
This caused a valve to blow which let in thousands of tonnes of water causing the ship to almost sink and leading to extensive damage.
640 men were killed when the South African troop carrier was hit by a cargo ship in 1917.
The 79-year-old man suffered a serious head injury in the Cranmer Road car park in Winton.
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