British tycoon Mike Lynch was among the 22 on board, celebrating his recent acquittal on fraud charges in the United States.
Divers and an underwater drone are searching for six people, including a UK tech tycoon and an international banker, believed to have been trapped when a luxury superyacht sank off Sicily.
Among the six missing were technology entrepreneur Mike Lynch and his 18-year-old daughter Hannah, and Jonathan Bloomer, chairman of Morgan Stanley International, and his wife Judy.
Police divers on Tuesday resumed their search for six people believed to be trapped in the hull of the 56-metre (185-foot) British-flagged yacht, named Bayesian.
The yacht was anchored with 10 crew and 12 passengers on board when it was hit by a mini-tornado with a windsock before dawn on Monday.
Fifteen people, including a woman and her one-year-old baby, were rescued. The body of a man, said to be the yacht's chef, was found, who was born in Antigua.
The passengers were guests of Lynch, sometimes called Britain's Bill Gates, celebrating his acquittal in a massive US fraud case.
Lynch was acquitted in June of fraud and conspiracy charges in a U.S. federal trial related to Hewlett Packard's $11 billion acquisition of his company, Autonomy Corp.
The ship's resting place is about 50 metres (164 feet) underwater, a depth that required special precautions that complicated the work. Recovery teams said they were working in 12-minute shifts, a measure that slowed their efforts to reach the narrow interior of the wreck.
The yacht was moored about a kilometre off the coast when a storm hit just before 4am on Monday. Civil protection officials said they believed the boat was hit by a tornado over the water, known as a waterspout, and sank rapidly.
A grainy film taken by closed-circuit cameras from the shore, broadcast on the Giornale di Sicilia website, showed the Bayesian's illuminated 75-metre (246-foot) mast weathering the storm and then disappearing over the course of a minute.
The yacht's captain survived and prosecutors reportedly attempted to interview him.
Karsten Borner, captain of the Sir Robert Baden Powell, who rescued the 15 survivors who managed to get into a lifeboat, said he was close enough to see the Bayesian when the storm hit.
“A moment later, it was gone,” Borner said. “They said they went under the water and within two minutes they sank,” he added, citing survivors.
Rotating search teams, each consisting of two cave divers, worked Tuesday to open access points to gain access to the interior of the wreck, which lies at a depth far greater than most recreational divers are certified to reach. They used a remotely operated underwater vehicle (ROV) to assist in the search.
Divers have not yet been able to access the lower cabins because they were blocked by furniture that had been moved during the violent storm.
Rescuers said they assume the six missing people are in those cabins because the storm hit when most would be sleeping, but crews have not verified their presence there through portholes.
Charlotte Golunski, who survived the disaster, said she momentarily lost her one-year-old daughter Sofia in the water but then managed to hold her above the waves until a lifeboat inflated and they were both rescued, Italian news agency ANSA reported.
The father, identified by ANSA as James Emslie, also survived, as did Lynch's wife, Angela Bacares. Hannah Lynch, believed to be the couple's 18-year-old daughter, is among the missing.
The yacht, built in 2008 by Italian firm Perini Navi, was available for charter and was notable for its massive 75-metre-high (246-foot) aluminium mast, one of the tallest in the world.
