New details have emerged about the mysterious death of a Sydney model on board a billionaire's superyacht in Greece — and they raise more questions than answers.

Sinead McNamara, 20, had been working on the Mayan Queen IV for the past four months before her sudden death on Friday.

The luxurious US$140 million, 92 metre yacht is owned by Mexican mining magnate Alberto Baillères, who is worth an estimated AU$9.6 billion.

According to local media, Mr Bailleres left the yacht, which was anchored off the island of Kefalonia, on Tuesday — leaving Ms McNamara alone with the crew. Her body was reportedly found on the back of the boat two days later.

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What happened in the 48 hours after the billionaire's departure in the lead up to Ms McNamara's death is now the subject of an inquiry by local authorities.

"The Coast Guard of Kefalonia has ordered an investigation into the circumstances that led to the death of the 20-year-old Australian national as well as an autopsy-necropsy," In Kefalonia reported

The Mayan Queen was scheduled to set sail today but has been ordered to remain docked in the port of Argostoli until detectives have interviewed all crew members and a forensic examination of the vessel.

In a tragic development, local reports suggest desperate attempts were made to revive Ms McNamara at the scene before she died on route to hospital.

"Local port authorities were informed at 2am Friday morning that the body of the woman was found … at the back of the yacht," Kefalonian Mantata said.

The paper said officers from the port authority, crew members and a doctor "tried for long time to bring her back" before rushing her to a hospital in Argostoli.

Doctors made the decision to fly her to a private hospital in Athens but Ms McNamara died during the helicopter flight, local media said.

The Department of Foreign Affairs and Trade said it has offered support to the McNamara family.


"DFAT is providing consular assistance to the family of an Australian who died in Greece," a spokeswoman said.

Originally from Port Macquarie, Ms McNamara moved to Sydney five years ago.

She was travelling in the seaside town of Pylos on the southwest coast of Greece.

In her last Instagram post four days ago, Ms McNamara wrote about jetskiing in Komitata, Greece.

Ms McNamara had been working on yachts while travelling in Europe.

Just five days ago on Facebook, Ms McNamara posted a selection of photos with her big sister Lauren, writing "happy birthday to the most amazing big sister I could ever ask for, 5 days till I get to see you!!! Excitement is an understatement."

There has been an outpouring of grief of Ms McNamara's Instagram profile, from fans of her travel and modelling photography.

"Rest In Peace you gorgeous girl, life is so unfair," wrote @lilyrobinson.

A number of people have also posted comments asking about the circumstances of her death.

Alex's heart-felt Instagram post to Sinead. Photo / Instagram
Alex's heart-felt Instagram post to Sinead. Photo / Instagram

Ms McNamara writes on her Instagram page that she is a fan of "camping, 4WD, adventure and travel". She has 12.7k followers on the platform.

Australian YouTube star Alex Hayes posted the news to his social media accounts.

Hayes, who has more than 650k followers on Instagram posted the tragic news in an Instagram story, writing "Life is so precious gone was too soon. Such a beautiful human being. Will cherish all our memories. Rest in Peace you beautiful soul".