Salvaging the Costa Concordia
The final phases of one of the largest and most complicated marine salvage operations ever undertaken is getting under way off the coast of the Italian island of Giglio.
It will culminate with the removal of the 114,000 tonne cruise liner Costa Concordia, which has lain partially submerged in 50ft (15 metres) of water just offshore for more than two years.Continue reading the main story
The ship has been resting on five huge metal platforms, constructed and lowered to the sea bed, since being rolled upright in September 2013.
The latest phase of the operation involved pumping air into massive steel boxes known as caissons, attached to both sides of the hull.
This refloated the damaged ship some two metres off the sea bed. It will then be painstakingly shifted into deeper water and floated higher, in an operation expected to last six to seven days.
It will then be towed back to its home port of Genoa and scrapped.
The final cost of the salvage operation is estimated at some $1.2bn (£0.7bn), although cruise line Costa Crociere estimates that it has contributed some 765 million euros ($1,040m, £600m) to the Italian economy.
Thirty-two people died in the accident, which occurred after Captain Francisco Schettino allegedly steered the ship too close to shore, causing it to hit rocks and partially capsize. The body of one man - Indian waiter Russel Rebello - remains unaccounted for.Delicate parbuckling
In September 2013 the Costa Concordia was hauled upright in the most delicate phase of the recovery operation.
A process called "parbuckling" used pulling cables and the weight of water contained in caissons attached to the ship's exposed port side (left) flank to roll it upright.
Pulling jacks applying some 6,000 tonnes of force were then used to dislodge the vessel from the rocky sea bed.
Once it had rolled to a 25 degree angle, the ship then continued to rotate under its own weight and the weight of water in the caissons.
Once upright, the scale of damage to the submerged starboard (right) side - ground into a reef and crushed under the weight of the hull - became clear.
After parbuckling, work continued with the addition of further caissons on the starboard side to stabilise the wreck and prepare it for refloating and removal.
The project has faced many delays due to bad weather.
During earlier stages, there were fears that the wreck could slide into deeper water and sink completely so heavy steel anchor cables were added to stabilise it.
The vessel still contains tonnes of rotting food, furniture, bedding and passengers' belongings, and environmental contamination has been a constant risk.
Speaking at the start of salvage work in 2012, one of the project's directors, Franco Porcellacchia, told the BBC: "This is a very delicate and unusual operation. We have no reference here".
"So far we have recorded no pollution and the situation is being constantly monitored by the authorities."
"Dismantling it is another ball game".
The Costa Concordia was only hours into a cruise of the Mediterranean on Friday 13 January 2012 when disaster struck just off Giglio island.
- 13 Jan: Costa Concordia runs aground
- 31 Jan: Search for bodies abandoned
- 22 March: Five more bodies found in wreck
- 24 March: Fuel removal work completed
- 21 April: Salvage contract awarded to firms Titan Salvage and Micoperi
- 15 Oct: Capt Schettino appears at court inquiry
- 3 Apr: Largest support platform in position
- 9 July: Captain Schettino goes on trial
- 20 July: Five senior crew members convicted of manslaughter
- 17 Sept: Ship rolled upright in 'parbuckling' operation
- 14 July: Refloating operation begins
The huge vessel - which had more than 4,000 passenger and crew onboard - then lost power, drifted and partially capsized.
The evacuation was slow and chaotic, with conflicting information passed between the captain, the ship's crew and the coastguard authorities.
Capt Schettino has been charged with manslaughter, causing a shipwreck and abandoning ship. His trial began in July 2013, and he could face up to 20 years in prison if found guilty. He denies all the charges.
Five other senior crew members were convicted of manslaughter in 2013 and given sentences of up to two years and 10 months. But they may avoid prison due to appeals and plea bargains.