A sixth diver was spared from death on an expedition to explore caves in the Maldives that killed five others because she did not enter the water, it has emerged.

The woman, a student at the University of Genoa, stayed on board the yacht as her fellow researchers fatally descended to the sea floor in Vaavu Atoll on Thursday, Italian newspaper La Repubblica reported.

It is unclear why she chose not to dive, but the survivor is now heading back to her family in Italy.

Her diving companions, all Italian nationals, never resurfaced and were declared dead. So far, just one body has been located in caves 200ft below the surface.

Victims include 51-year-old marine biologist Monica Montefalcone; her 22-year-old daughter, Giorgia Sommacal; Muriel Oddenino of Turin; Gianluca Benedetti of Padua and Federico Gualtieri from Omegna.

Another 20 Italians were also aboard the yacht. It is not clear what their role in the expedition was, but they have been offered assistance by the Italian Embassy in Sri Lanka.

The group had boarded the ‘luxury’ Duke of York yacht, a foreign-operated live-aboard diving vessel, and they disappeared near Alimatha, one of the atoll’s most popular diving spots.

Aircraft and speedboats were deployed for a major search after the group of five was reported missing on Thursday afternoon, the Maldives National Defence Force (MNDF) said.

One of the victims has been named as Monica Montefalcone, a professor and researcher at the University of Genoa
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One of the victims has been named as Monica Montefalcone, a professor and researcher at the University of Genoa

Giorgia Sommacal, 22, Monica Montefalcone's daughter, also died
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Giorgia Sommacal, 22, Monica Montefalcone’s daughter, also died

Muriel Oddenino was also a researcher at the University of Genoa
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Muriel Oddenino was also a researcher at the University of Genoa

‘One body has been found among five divers who went diving in Vaavu Atoll,’ the statement said.

‘The body was found inside a cave. It is believed that the remaining four divers are also inside the same cave, which extends to a depth of about 60 metres (200 feet).’

Montefalcone was a respected marine biologist, TV personality, and professor of Tropical Marine Ecology and Underwater Science at the University of Genoa.

Today, her devastated husband, Carlo Sommacal, said his wife was an ‘expert’ diver and ‘never reckless’.

‘Monica would never have put the lives of her daughter and the other children at risk through recklessness. Something happened down there.’

Rescue teams on Friday continued their search for the remaining bodies, but local authorities have said the recovery operation is ‘high risk’ due to adverse weather conditions.

Meanwhile, police have launched an investigation into the tragedy, but the cause of death remains unknown at this time.

Authorities have not ruled out several scenarios, with police probing whether bad weather may have affected the divers’ visibility.

Weather conditions at the dive site on Thursday were unfavourable, with winds blowing between 25 and 30 miles per hour.

The meteorological service had issued a yellow alert for the area yesterday morning.

Gianluca Benedetti of Padua was named as one of the people who died on the dive
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Gianluca Benedetti of Padua was named as one of the people who died on the dive

According to Italian news outlet La Repubblica, the fact that none of the five divers managed to resurface suggests the group may have become lost within an underwater cave.

With little light and poor visibility due to bad weather, they may have lost their bearings, panicked, and perhaps run out of air while trying to find their way out.

Police also haven’t ruled out the possibility that one of the five may have become stuck while the others ran out of air or panicked while trying to free their colleague.

Diving experts have also been speculating on various hypotheses.

According to local media, one of the most widely accepted hypotheses by the coast guard and experts is oxygen toxicity. This phenomenon occurs if the tank’s mixture is inadequate, making oxygen toxic at certain depths.

‘At 50 meters of depth in the sea, there are several risks; it’s a real tragedy,’ says Alfonso Bolognini, president of the Italian Society of Underwater and Hyperbaric Medicine.

‘There are several hypotheses we can make right now: an inadequate breathing mix can create a hyperoxic crisis when there’s an increase in the partial pressure of oxygen in the tissues and blood plasma, which can cause neurological problems.

‘Inside a cave at 50 meters of depth, all it takes is a problem for a diver or a panic attack for a diver,’ he adds, saying that ‘the agitation causes the water to become cloudy and can impair visibility.

‘In these cases, the panic component could lead to even fatal errors.’

The yacht company for the Duke of York, as stated on its official website, provides nitrox – the breathing mixture for scuba diving, composed of nitrogen and oxygen.

It is also unclear whether the Italians’ dive, being at a depth of over 160ft, was regulated, according to the MNDF.

Federico Gualtieri who died in the Maldives
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Federico Gualtieri who died in the Maldives

Meanwhile, it has been revealed that there was no local guide to accompany the group into the cave, as required by Maldivian law.

Investigators are also trying to determine whether the group used an ‘Ariadne’s thread’ – a rope used by divers while exploring caves to help them stay close together and find the entrance and exit to the cavities.

The use of the rope is mandatory in certain caves.

In Italy, the tragedy has sent shockwaves through the academic world.

Milan-born Montefalcone worked at Distav, the Department of Earth Sciences. In the Maldives, she was the scientific director of the island monitoring campaign.

Her department has described her as ‘the most experienced, the best, the most competent.’

Montefalcone survived the 2004 Boxing Day tsunami when it struck the Maldives.

Her daughter Giorgia had inherited her mother’s passion for sea life and diving, having completed a degree in biomedical engineering at the University of Genoa.

Oddenino, a 31-year-old marine biologist and ecologist, was Montefalcone’s colleague.

She was an experienced diver and authored scientific publications. She was described by a loved one as ‘sweet and sensitive’.

Benedetti, 44, was an operations manager, a diving instructor and a boat captain.

According to initial reports, the five tourists who died had boarded the Duke of York (above), a foreign-operated live-aboard diving vessel, and they disappeared near Alimatha
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According to initial reports, the five tourists who died had boarded the Duke of York (above), a foreign-operated live-aboard diving vessel, and they disappeared near Alimatha

The Maldives, a nation of 1,192 tiny coral islands scattered some 500 miles across the equator in the Indian Ocean, is a luxury holiday destination popular with divers. The group went missing close to Alimatha (above)
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The Maldives, a nation of 1,192 tiny coral islands scattered some 500 miles across the equator in the Indian Ocean, is a luxury holiday destination popular with divers. The group went missing close to Alimatha (above)

After working in banking and finance for several years, he turned his passion for diving into a full-time career and moved to the Maldives in 2017.

He was the operations manager and skipper aboard the Duke of York, the diving yacht that the group used for their expedition.

He was described by Albatros Top Boat, the Duke of York’s operator, as ‘energetic, extremely sporty, and a lover of reading, classic cinema, and chess.’

Speaking about her son’s tragic death, Benedetti’s mother told Italian news outlet Gazzettino: ‘I heard the news from the embassy. I can’t say anything, and you can only imagine the pain.’

Gualtieri, 31, was a scuba diving instructor and had recently graduated from the University of Genoa with a degree in marine biology and ecology.

He had previously praised his professor, Montefalcone, saying: ‘Ever since I met her, she has always been my guide, encouraging me to follow my dreams and passions.’

His girlfriend, Noemi De Luca, paid a tribute to him on social media, saying: ‘Three years together, but always and forever in each other’s hearts. You’ll always be in my heart.’

She added: ‘Just know that I was, am and always will be proud of you.’

Marine biologist Oddenino, from Turin, was described by a loved one as 'sweet and sensitive'
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Marine biologist Oddenino, from Turin, was described by a loved one as ‘sweet and sensitive’

Sommacal had inherited her mother's passion for diving
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Sommacal had inherited her mother’s passion for diving

Local officials said it was the worst single diving accident in the nation.

Maldives Minister of Tourism Mohamed Ameen said coast guard officers and security forces were scouring remote seas around where the divers were reported missing on Thursday afternoon.

‘I am deeply saddened by the tragic deep diving accident in Vaavu Atoll today,’ Ameen said in a statement.

‘The coastguard and all relevant authorities are actively engaged in the search and recovery operation.’

The Duke of York’s operator declined to comment when approached for comment.

Italy’s Ministry of Foreign Affairs has confirmed the incident.

‘Following an accident during a scuba dive, five Italians died in the Vaavu atoll, in the Maldives,’ a statement read.

The Ministry of Foreign Affairs and the Italian Embassy in Colombo, Sri Lanka, have said they have been ‘contacting the victims’ families to provide any necessary consular assistance’.

Rome’s prosecutor’s office has opened an investigation into the death of the five Italians.

The Maldives, a nation of 1,192 tiny coral islands scattered some 500 miles across the equator in the Indian Ocean, is a luxury holiday destination popular with divers, who often stay at secluded resorts or on dive boats.

Local regulations allow dives to a maximum depth of 98 feet, but experienced professionals are known to go deeper.

Diving and water-sport-related accidents are relatively rare in the South Asian nation, although several fatal incidents have been reported in recent years.

A British woman tourist died while diving in December, and her distraught 71-year-old husband died a few days later after falling ill.

A 26-year-old Japanese tourist went missing after a diving expedition near the capital in June.

Local media reported last year that at least 112 tourists had died in marine-related incidents in the archipelago over the previous five years, including 42 in diving or snorkelling accidents.