Cave-diving experts are among the rescuers still hoping to find survivors trapped underwater on the superyacht Bayesian that was sunk by a tornado off Sicily. It is thought the only hope of survival for the six passengers unaccounted for – tech tycoon Mike Lynch and his 18-year-old daughter, Morgan Stanley executive Jonathan Bloomer and his wife Judy, Clifford Chance lawyer Chris Morvillo and his wife Neda – is that they are in an air pocket on the doomed £30m vessel. Among those carrying out the search are two cave divers attempting to navigated the dark, tight corridors of the “fully intact” yacht, which is now lying at a depth of 49 metres.

“They can stay underwater for a maximum of 12 minutes, two of which are needed to go up and down,” emergency responder Luca Cari told Italian daily Giornale Di Sicilia . “So the real time to be able to carry out the search is 10 minutes per dive.” For latest updates on the sunken yacht, follow our live blog by clicking here .

The rescue divers have been able to enter the lounge of the luxury vessel via a ladder but were still trying to enter the rest of the yacht late on Tuesday. Mr Cari explained how the divers had identified a glass window of the Bayesian from which they could gain greater access, though it will first need to be removed in order to gain access. The window is 3cm thick, making removal difficult.

A preliminary search of the command bridge found a mess of cables but nothing of the missing guests. “The .