Engineers have begun lifting the wrecked Costa Concordia liner in one of the most complex salvage operations ever attempted.
The 114,500 tonne cruise liner has lain on its side for more than 20 months, dominating the tiny port in the Tuscan holiday island of Giglio where it hit rocks on January 13, 2012, killing 32 people.
After a three-hour delay caused by an overnight storm which interrupted final preparations, salvage crews started the all-day operation at around 9am (7am GMT).
Engineers will attempt to “parbuckle” the ship – a series of 11 towers with hydraulic mechanisms controlling 205kg cables slung under the ship and attached to its side will rotate the vessel at a rate of about 3 meters per hour until it is sitting on six specially built platforms drilled into the granite rock bed.
Eleven large tanks, the size of multistorey buildings, have been welded to the side of the Concordia that is out of the water to give leverage and buoyancy while two other tanks will act as a sort of "neck brace" to stabilise the ship’s bow.
The tanks will be filled with water on the exposed side of the vessel to help rotate it upward, using gravity to pull the exposed side down, and once upright, those tanks along with others on the opposite side will be filled with air to help float the ship up off the reef so it can be towed away.
A multinational team of 500 salvage engineers has been on the island for most of the past year, stabilising the wreck and preparing for the start of the lifting operation, which must be completed before the vessel can be towed away to be broken up.
"We have done parbuckling before but never on a location like this," Nick Sloane, the South African engineer coordinating the recovery for contractors Titan Salvage, told Reuters as the final preparations began.
"She is on the side of a mountain on the seabed, balanced on two reefs and she is a really large ship - she's three football fields long, a hundred thousand tonnes plus... So it's never been done on this scale," he said.
The cost of the operation is so far estimated at more than €600m (£500m) and is expected to be the most expensive maritime wreck recovery ever, accounting for more than half of an overall insurance loss of more than £690m.
The operation is scheduled to take 10-12 hours with the most delicate phase expected at the beginning, when hydraulic pulleys begin to shift thousands of tonnes of metal off the rock bed.
Engineers have lifted the ship a few centimetres to detach the metal from the jagged rock spur but it is unclear how the damaged structure will react to being lifted upright.
During the operation, crews will look for the bodies of crew member Russel Rebello and passenger Maria Grazia Trecarichi.
Once the ship is upright, salvage teams will spend a number of months stabilising it and preparing for it to be re-floated with the aid of additional giant buoyancy tanks before it is towed away for scrap, probably next spring.
The Costa Concordia, the length of three football pitches which can carry more than 4,000 passengers and crew, sank when rocks tore a huge gash in its hull after it came too close to shore at the start of a Mediterranean cruise.
Captain Francesco Schettino has been charged with multiple counts of manslaughter and causing the wreck but the accident has also raised questions about the risks and costs of operating and insuring such vast ships.
Engineers say they are confident the operation will be a success, although the process has never before been attempted under such difficult conditions on a vessel of this size.