Police divers resumed searching Tuesday for six people believed trapped in the hull of a superyacht that sank in deep seas off Sicily, including a British tech magnate who was celebrating his recent acquittal on fraud charges with the people who had defended him at trial. The resting place of their sailboat is some 50 meters (164 feet) underwater off Porticello — a depth that requires special precautions: Rescue 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 Bayesian, a 56-meter (184-foot) British-flagged yacht, was moored about a kilometer (a half-mile) offshore when a storm rolled in before 4 a.

m. Monday. Civil protection officials said they believed the ship was struck by a tornado over the water, known as a waterspout.

Fifteen of the 22 people aboard survived, including a mother who reported holding her 1-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 located in the wreckage.

They include the tycoon Mike Lynch, who was once hailed as Britain’s king of technology and was cleared in June of fraud and conspiracy charges in a U.S. federal trial related to Hewlett Packard’s $11 billion takeover of his company, Autonomy Corp.

Also unaccounted for are Christopher Morvillo, one of Lynch’s lawyers, and Jonathan Bloomer, .