One man has died and six are missing after a luxury yacht sank off the coast of Sicily due to extreme weather conditions.
The 56-metre, British-flagged Baysian was carrying 22 people – 12 passengers and 10 crew – when it was hit by a severe storm producing a water tornado early Monday morning.
Fifteen people have been rescued but searches are ongoing for those still missing, including British tech tycoon Mike Lynch.
Here’s what we know so far about the tragedy and how it happened:
What happened to the yacht?
Witnesses said the Basin was hit by a sudden and powerful storm early Monday morning.
The ship was reportedly anchored at sea off the harbour of Porticello, a small fishing village east of Palermo, when it was hit by what the Italian coast guard described as a “violent storm”.
The storm was so severe that water tornadoes, spinning columns of air and mist, appeared over the ocean.
The ship disappeared into the sea at around 5am local time (4am BST).
A doctor treating survivors said the boat “capsized within minutes.”
Witnesses told Italian news agency Ansa that the Basian’s anchors had been dropped when the storm hit, snapping its 72-meter (236-foot) aluminium mast in half, causing the ship to lose balance and sink.
But search and rescue divers said the vessel was “largely intact” on the seabed, raising questions about whether the mast had broken off.
Matthew Shank, chairman of the Maritime Search and Rescue Council, said the ship’s unusually tall mast may have contributed to the sinking.
He told BBC Radio 4’s Today programme that the mast acted like a sail in strong winds “particularly because it was so tall”.
High winds could have caught the mast and capsized the yacht, he said.
Karsten Borner, captain of a nearby boat, said after the storm passed, his crew realised the yacht they had been sailing behind had disappeared.
“We saw red flare signals, so myself and the first mate headed to the scene and found the drifting life raft,” he told Reuters.
The crew took on board several survivors, including three seriously injured.
Another witness, Fabio Cefalu, the captain of the trawler, said he had been preparing to go out fishing when he saw lightning and so stayed in port.
“I saw fire at sea at around 4:15 a.m.,” he said, according to the EVN news agency.
“We waited for this water tornado to pass. Ten minutes later, we went out to sea and found the cushions, the remains of the sunken ship and everything that was on the deck in the water. But there was nobody in the water.”
Another fisherman said he saw the yacht sink “with his own eyes.”
Witnesses told daily newspaper Giornale di Sicilia that they were at home when the tornado struck.
“Then I saw the ship. It only had one mast and it was very big,” he said.
Soon afterwards he went to the Gulf of Santa Nicolicchia in Porticello to get a better view of what was going on.
He added: “The boat was still afloat but suddenly it disappeared. I saw it sink with my own eyes.”
One survivor, British tourist Charlotte Gornski, told Italian newspaper La Repubblica how she had lifted her one-year-old daughter Sofia to keep her from drowning.
She said the couple and their partner James survived because they were on deck when the yacht sank.
They were awakened by “thunder, lightning and waves that made the boat dance” and felt like “the end of the world” before being thrown into the water.
“For two seconds I lost my daughter in the water but then I quickly grabbed her in the middle of the raging waves,” Charlotte said.
She added: “I held my arms out to keep her from drowning and did my best to keep her afloat.”
“It was pitch black. I couldn’t keep my eyes open in the water. I screamed for help but all I could hear was other people screaming around me.”
What’s new in search?
Six passengers remain missing and the Palermo coast guard said search and rescue operations were continuing “without pause”.
The search began on Monday, with specialist divers working at the site since the early hours of Tuesday morning.
A diver told Italian media that the yacht was lying on the seabed about 50 metres below the surface and was “virtually intact”.
Italy’s fire and rescue service said the hull of the ship was filled with furniture and various objects.
Divers are trying to find a way to access the yacht’s cabin but have only 10 minutes to search in each dive before returning to the surface, Italian news agency Ansa reported.
One-centimeter-thick glass windows are also being considered as a possible entry point.
Francesco Venuto, a spokesman for Sicily’s Civil Defense, told the BBC on Monday that rescuers feared the bodies of the missing people “must be inside the boat”.
“They’ve been searching all day with helicopters and boats and haven’t found anything. It doesn’t make sense. In a situation like this, they should find something by now,” he added.
Salvatore Cocina, head of Sicily’s civil defence department, said a specialized cave search and rescue diving team would arrive from Rome on Monday and hope to “make progress” by midnight or at the latest by Tuesday morning.
The UK’s Maritime Accidents Investigation Branch sent a team of four investigators on Monday to carry out a preliminary investigation into the sinking of the Baysian, the BBC reported.
Who was on board?
There were 22 people on board the ship when the storm hit: 12 passengers and 10 crew members.
The body of one man has been recovered. His identity has not been officially confirmed, but the Palermo coast guard said he was the ship’s cook. His nationality has not been confirmed.
Among the six still missing is Mike Lynch, a 59-year-old IT entrepreneur known by some as the “British Bill Gates”.
Lynch founded the software giant Autonomy in 1996 and was awarded the Order of the British Empire (OBE) in 2006 for his services to enterprise.
In June he was cleared of suspicion of large-scale fraud relating to the $11 billion (£8.64 billion) sale to the US company Hewlett-Packard.
He later told the BBC that he had been able to prove his innocence only because he had the financial means to pay the huge legal costs.
Others still missing include Lynch’s 18-year-old daughter Hannah, Morgan Stanley International Bank chairman Jonathan Bloomer and Clifford Chance Bank lawyer Chris Morbillo.
Mr Lynch’s wife, Angela Bacarès, was among 15 people rescued, eight of whom were being treated in hospital, the Italian coast guard said.
Charlotte Gornski, her husband and daughter Sophia were also rescued and uninjured but were taken to hospital for examination.
She said she was on a yacht with a group of colleagues.
The daily newspaper Il Giornale di Sicilia reported that the ship was carrying mostly British passengers, but also people from New Zealand, Sri Lanka, Ireland and Britain-French.
A doctor in Palermo said the “very tired” survivors were “constantly asking about the missing.”
Doctor Domenico Cipolla told Reuters that one of the women he treated described the trip as a “corporate trip” and that some of the passengers were “very young”.
“There were a lot of people there – work colleagues, friends, couples and a few friends,” he added.
What are water tornadoes and why do they occur?
Water tornadoes are similar to tornadoes and can occur over oceans, seas, and large lakes.
The western half of the Mediterranean has been hit by severe storms since the middle of last week.
A band of severe weather passed over the northern coast of Sicily between Sunday night and Monday morning.
“A waterspout is a tornado that forms over water rather than on land,” BBC weather forecaster Matt Taylor said.
“They can form at the base of cumulonimbus or thunderclouds during severe storms.
“Turbulence and winds blowing in slightly different directions around the cloud can cause rotation below the base of the cloud, which can lead to the formation of a plume.
“They produce strong winds like a tornado, but instead of stirring up dust and debris, they produce a mist of water around the spinning column of air.”
What is Bayesianism and who owns it?
The superyacht can accommodate up to 12 guests in six suites and can be rented for up to 195,000 euros (£166,000) per week.
It was built in 2008 by the Italian company Perini Navi.
The registered owner of Bayesian is Revtom Ltd, based in the Isle of Man.
The yacht is understood to be named after Bayes’ Theorem, which formed the basis of Lynch’s doctoral thesis and the software that made his fortune.
Mr Lynch’s wife, Bakales, is listed as the sole legal owner of Rebtom, which is registered in the Isle of Man.
According to ship-tracking website VesselFinder, the Bayesian has completed several voyages, calling at various ports in Sicily in recent days.
A spokesman for Camper & Nicholsons International, which manages the 2008-built ship, told BBC Verify: “Our priority is to support the ongoing search effort and provide any necessary assistance to the rescued passengers and crew.”