British tycoon Mike Lynch was among the 22 onboard, celebrating his recent acquittal on fraud charges in the US.

Divers and an underwater drone are searching for six people, including a tech tycoon from the United Kingdom and an international banker, believed trapped when a luxury superyacht sank off Sicily.

Among the six missing were tech entrepreneur Mike Lynch and his 18-year-old daughter Hannah, and Jonathan Bloomer, the chair of Morgan Stanley International, and his wife Judy.

Police divers on Tuesday resumed the search for the six people believed trapped in the hull of the British-flagged 56-metre (185 feet) yacht, named Bayesian.

The yacht was anchored with 10 crew and 12 passengers on board when it was struck by a waterspout mini-tornado, before dawn on Monday.

Fifteen people, including a woman and her one-year-old baby, were rescued. The body of one man – reported to be the yacht’s Antiguan-born chef – was found.

The passengers were guests of Lynch – sometimes referred to as Britain’s Bill Gates – to celebrate his acquittal in a massive fraud case in the United States.

Lynch, was cleared in June of fraud and conspiracy charges in a US federal trial related to Hewlett Packard’s $11bn takeover of his company, Autonomy Corp.

The resting place of the sailboat is some 50 metres (164 feet) underwater – a depth that required special precautions that complicated the work. Recovery crews said they were working in 12-minute shifts, a measure that slowed down their efforts to reach the cramped inside of the wreck.

The yacht was moored about a kilometre (a half-mile) offshore 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, known as a waterspout, and sank quickly.

Grainy film from closed-circuit cameras from shore, broadcast on the website of the Giornale di Sicilia, showed the illuminated 75-metre (246-foot) mast of the Bayesian weathering the storm and then disappearing over the course of a minute.

The yacht’s captain survived, whom prosecutors reportedly sought to interview.

Karsten Borner, captain of the Sir Robert Baden Powell, which rescued the 15 survivors who managed to get into a lifeboat, said he was close enough to be able to see the Bayesian as the storm came in.

“A moment later, she was gone,” Borner said. “They said they went flat on the water and were sunk in two minutes,” he added, 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. They were using a remote-controlled underwater vehicle, or ROV, to help in the search.

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 said they assume the missing six are in those cabins because the storm struck when most would be sleeping, but the teams have not verified their presence there through portholes.

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, as did Lynch’s wife, Angela Bacares. Hannah Lynch, reportedly the couple’s 18-year-old daughter, is among the missing.

The yacht, built in 2008 by the Italian firm Perini Navi, had been available for charter and was notable for its massive 75-metre-tall (246-foot-tall) aluminium mast, one of the tallest in the world.