The mystery surrounding the death of Australian woman Sinead McNamara aboard a Mexican billionaire’s super yacht continues as the Mayan Queen IV left the Greek island of Kefalonia on Monday night (AEST).

The 20-year-old Instagram model was reportedly on the final day of a four-month stint working as a crew member on the Mayan Queen IV when she died on board the ship early Friday as it lay anchored near Kefalonia.

The yacht had been ordered to remain moored off the Greek coast as authorities investigated her death, but the MarineTraffic website showed the vessel off the coast of Sicily heading west on Tuesday morning.

The $US140 million ($194 million) yacht, owned by Mexican billionaire Alberto Bailleres, was released after investigators reviewed CCTV footage from the vessel and interviewed the crew, Greek media reported.

The UK’s Times newspaper quoted Greek authorities as saying Ms McNamara’s cause of death appeared to be suicide after a crew member found her tangled in a rope on the rear deck of the yacht.

Greek media reported she was still alive when found, but attempts to revive her on the boat and in a hospital were unsuccessful.

No suicide note is believed to have been found on board the vessel and investigators were working to piece together her final hours.

A spokesman for the Hellenic coast guard told Fairfax media there would be no official update on the case on Tuesday (AEST).

Only crew were on the yacht when Ms McNamara was found. Photo: marinetraffic.com

Fairfax quoted an unnamed source close to the investigation as saying that an autopsy was yet to be completed, and the circumstances surrounding the death were not yet confirmed.

But the source said all indications so far were that there were no suspicious circumstances, a summation backed up by the decision to allow the Mayan Queen IV to leave port.

Members of the Bailleres family – which owns one of the world’s largest silver mines and Mexico’s second-largest mining company – had been on the yacht, but had left to return to Mexico days before the incident.

Authorities confirmed that only crew members were on board the ship when Ms McNamara’s body was found.

Ms McNamara’s mother and sister were on their way to Greece to meet her for a holiday when news of her death surfaced.

The Department of Foreign Affairs and Trade is providing consular assistance to the family.

My head is all over the shop today 🌪🌋 take me back to this where my only worry was not cracking my skull open 💉

A post shared by Salt Bby 💦 (@sineadmcnamara) on Aug 19, 2018 at 6:07am PDT

Ms McNamara who had more than 14,000 Instagram followers, posted last month that while she enjoyed living and working on the yacht, she was looking forward to returning to Australia.

“Yep I think I have it pretty good. Today’s a day for being grateful anddd (sic) it’s less then a month till I get to see my family & friends in Aus. Excitement overload!” she posted.