Divers battle 10-minute dive window and debris in yacht search

Rescue operations continue into their second day for those still missing after the Bayesian yacht sank off the coast of Sicily

Rescue teams searching the luxury yacht off the coast of Italy for six missing people are facing tough conditions, including a short dive window and scattered debris on board, an expert has told the BBC.

Crews have spent the past two days searching the ship, and trying to access the areas where the passengers may be.

The Bayesian yacht was carrying 22 people when it sank in freak weather conditions early on Monday.

One man has been confirmed to have died in the incident, and a search for the six people still missing continues - the Italian coastguard believes they could still be trapped in the sunken yacht.

“You have current, you have wind, you have waves, you have everything," Guy Thomas, a diving instructor and a member of the special rescue team of the Italian Red Cross, tells the BBC.

He is not involved in this specific rescue attempt, but says he believes "there will be a lot of debris" - making conditions for rescue crews challenging.

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The Italian fire department has said that its divers initially struggled to even get inside the vessel, as furniture was obstructing the passageway.

And the ship's hull's location - tilted at a 90-degree angle - has created similar difficulties, the inspector of the diving unit, Marco Tilotta, told the Reuters news agency.

The issue for rescuers is that when a boat goes down in a tornado-like storm, everything that is not attached will either fall or float, Mr Thomas explains.

Rescuers also face challenges trying to access the part of the yacht where they believe the missing passengers may be.

"We know the boat sank quickly," spokesman Vincenzo Zagarola told the PA news agency, "we suppose that the six people missing may not have had time to get out".

The timing of its sinking - at night - means those missing were likely to have been in the yacht's inner cabins if they did not have time to escape.

"Going into all the cabins," Mr Tilotta said "is a really hard and difficult job."

Because of the depths at which the wreckage sits - about 50m (164ft) below the surface - divers are limited to how long they can spend under water.

After descending to the wreckage, they only have 10 minutes to search the Bayesian before needing to resurface, according to the head of emergency communications of Italy's fire and rescue department, Luca Cari.

During deeper dives, Mr Thomas says, "your body starts to accumulate nitrogen, and your body needs to stop and go back up".

If a diver returns to the surface too quickly, the nitrogen bubbles don't have time to dissipate - leading to a dangerous condition known as decompression sickness, also known as the bends.

The rescue attempt poses a real risk for the divers themselves, Mr Thomas says, with the possibility that they too could get stuck inside the yacht while carrying a limited amount of air.

"You could get lost in the ship," he says. "It's not a huge ship, there’s probably going to be a limited amount of light."

Finally, there's the issue of time.

In these situations, Mr Thomas says "you need to get there immediately".

"When the boat goes down, rescue divers are trying to find people alive in air bubbles.

"But most people will not be in an air bubble."

And when asked about the likelihood of any of the six people missing being found alive on the vessel, Mr Zagarola - the Italian coastguard spokesman - was not optimistic.

"Never say never, but reasonably the answer should be not."