The ⁠bodies ​of ⁠four ‌missing Italian scuba ‌divers ‌who died ⁠last week while exploring underwater caves have now been located, the Maldives government said.

A group of five Italian divers died while attempting to explore caves at a depth of 50m (164ft) in the Vaavu Atoll on Thursday, Italy’s foreign ministry said. The body of one of the divers was recovered from the opening of the cave on the same day.

On Monday, a team of three Finnish divers arrived to plan a fresh search for the bodies of the divers, Divers Alert Network Europe said.

Earlier, a high-risk operation to recover the bodies had to be suspended following the death of a Maldivian diver from decompression sickness.

Mohamed Mahudhee, a member of the Maldivian National Defence Force, died of underwater decompression sickness after being transferred to a hospital in the capital on Saturday, Maldives presidential spokesperson, Mohamed Hussain Shareef, said.

Mr Shareef said three Finnish divers, experts in deep and cave diving, arrived in the archipelago nation and joined the Maldives coastguard in a meeting aimed at mapping a new search strategy.

Mahudhee was buried with military honours in a funeral attended by president Mohamed Muizzu on Saturday night. The diver was part of the group that had briefed Mr Muizzu on the rescue plan when he visited the search site on Friday.

What is decompression sickness?

Decompression sickness occurs when depressurised gas, usually nitrogen, exits the solution phase in tissues and obstructs the circulation by forming bubbles. This can happen after a quick ascent from deep-sea diving, according to the National Library of Medicine.

Italian foreign minister Antonio Tajani said they would do everything possible to bring home the bodies and offered condolences for Mahudhee’s death.

The victims have been identified as Monica Montefalcone, an associate professor of ecology at the University of Genoa; her daughter, Giorgia Sommacal; marine biologist Federico Gualtieri; researcher Muriel Oddenino; and diving instructor Gianluca Benedetti, according to the Maldivian government.

Benedetti’s body was recovered on Thursday from near the mouth of the cave.

What happened inside?

While no one immediately knows exactly what happened inside the caves, since there were no survivors among the five who entered them, the recovery of four bodies and the cave’s layout have led to common theories.

The group entered a complex underwater cave in Vaavu Atoll at around 50m of depth on the morning of Thursday, a depth well beyond the permitted recreational diving limit of 30m.

The cave system, which consists of three large chambers connected by narrow passages, overhangs, swim-throughs, and tunnels in a coral reef structure, with potential strong currents, low visibility, especially in rough weather, silt, and tight spaces. It stretches up to about 60m.

The divers gave a distress call at around 1.45pm and were reported missing after they failed to resurface.

Dive master Maurizio Uras has suggested “oxygen toxicity” inside the cave might have contributed to the incident.

“It’s a phenomenon that can happen when you dive very deep,” he said to Italian news agency Agi: “If the oxygen mix is inadequate, oxygen can become toxic at certain depths.

“Weather conditions are also an important factor and we have to consider that the Indian Ocean is not the Mediterranean, which is relatively calm.”

“There [in the Indian Ocean], there are strong currents which I imagine can pull from one side to the other. A real danger.”

The weather conditions were rough in the area, with a yellow warning issued for passenger boats and fishermen on that day. Conditions included rough weather and currents, which can disorient divers, stir up silt, reducing visibility to near zero, and complicate navigation or exit.

Speaking to Italian outlet Adnkronos on Thursday, pulmonologist Claudio Micheletto said it was likely that “something went wrong with the tanks” during the dive.

Mr Micheletto, director of pulmonology at the University Hospital of Verona, said oxygen toxicity – also known as hyperoxia – can be among the deadliest complications during deep dives.

“Death from oxygen toxicity, or hyperoxia, is one of the most dramatic deaths that can occur during a dive – a horrible end,” he told Adnkronos.

When diving, scuba divers breathe compressed air, which is 21 per cent oxygen and 79 per cent nitrogen. But some divers use a specialised gas mixture known as nitrox, or enriched air nitrox, which contains more oxygen and less nitrogen than regular compressed air.

“When you breathe in too high a concentration of oxygen, the gas becomes toxic to the body,” he said.

“During the dive, dizziness, pain, altered consciousness and disorientation occur, making it impossible to surface.”

Alfonso Bolognini, president of the Italian Society of Underwater and Hyperbaric Medicine, said panic may have also contributed to the incident, among other factors.

“Inside a cave at a depth of 50m, all it takes is a problem for a diver or a panic attack for a diver,” he said. “The agitation will cause the water to become cloudy and can impair visibility”, which, in turn, can lead to “fatal errors.”

But he added that it was not easy to conclude what exactly may have happened at the bottom of the sea.

The Italian ministry said it was coordinating with Divers Alert Network, a specialist diving organisation, to support recovery operations and the repatriation of the bodies.

It said the recovery teams so far have explored two of the three chambers, but the search was limited due to considerations over oxygen and decompression.

The divers are now drawing up a plan to explore the third chamber, the ministry added.