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.