Police divers have resumed searching for six people believed trapped in the hull of a superyacht that sank in a storm off Sicily, including a British tech magnate recently acquitted of fraud charges, his lawyer and a key defence witness at trial.
The resting place of the luxury sailboat, off Porticello, is 50 metres under water - a depth that requires special precautions: rescue crews said they were working in 12-minute shifts, a measure that slowed down their work to reach the cramped inside of the wreck.
The Bayesian, a 56m British-flagged luxury yacht, was moored about a kilometre off Ponticello when a storm rolled in before 4am on Monday.
Civil protection officials said they believed the ship was struck by a tornado over the water.
Fifteen of the 22 people aboard survived, including a mother who reported holding her one-year-old baby over the waves to save her.
One body has been recovered, identified by officials as the on-board chef.
Fire rescue officials have said the other six on board will be considered missing until they are found in the wreckage.
Karsten Borner, the captain of the Sir Robert Baden Powell, which rescued the survivors who managed to get into a lifeboat, said he was close enough to be able to see the Bayesian as the weather came in but found it had disappeared after the storm cleared.
“They said they went flat on the water and were sunk in two minutes," Borner said, quoting the survivors.
The rotating search teams, each made up of two specialised cave divers, worked on Tuesday to open up access points to get inside the wreck, which lies at a depth far beyond what most recreational divers are certified to reach.
The divers have not yet been able to access the below-deck cabins because they were blocked by furniture that had shifted during the violent storm.
Rescue crews assume the missing six are in those cabins because the storm struck when most would be sleeping.
Luca Cari, a spokesman for the rescue teams, said the search was proceeding much more slowly than another big shipwreck in Italy, the 2012 Costa Concordia cruise ship that flipped on its side off Tuscany's coast, because of the depth of the wreck and the space divers have to manoeuvre.
Among those missing was Mike Lynch, who was once hailed as Britain’s king of technology. He was cleared in June of fraud and conspiracy charges in a US federal trial related to Hewlett Packard’s $US11 billion ($A16 billion) takeover of his company, Autonomy Corp.
His wife, Angela Bacares, survived.
The sailing holiday appeared to be something of a celebration after Lynch's acquittal.
Some of the people who stood by Lynch throughout the ordeal were on board, including one of Lynch’s US lawyers, Christopher Morvillo, and Morvillo’s wife.
Both are also unaccounted for, according to the civil protection agency.
Also missing was Jonathan Bloomer, a chairman at Morgan Stanley International and the former head of the Autonomy audit committee who testified in Lynch’s defense, and his wife.
Charlotte Golunski, who survived the disaster, said she momentarily lost hold of her one-year-old daughter Sofia in the water, but then managed to hold her up over the waves until a lifeboat inflated and they were both pulled to safety, Italian news agency ANSA reported.
The father, identified by ANSA as James Emslie, also survived.
The yacht, built in 2008 by the Italian firm Perini Navi, was carrying 12 passengers and 10 crew.
According to online charter companies, it has been available for charter for 195,000 euros (A320,000) a week and is notable for its massive 75m aluminium mast, one of the tallest in the world.
