An 80-year-old Australian woman has been found dead on a Great Barrier Reef Island after being left behind by the cruise ship she was travelling on.

The woman had been hiking on Lizard Island, 250km (155 miles) north of Cairns with fellow passengers from the Coral Adventurer cruise ship on Saturday but is believed to have broken off from the group to have a rest.

The ship left the island around sunset but returned several hours later after the crew realised the woman was missing. A major search operation found her body on Sunday morning. No details have been released.

The Australian Maritime Safety Authority (Amsa) said it was investigating and would meet the ship's crew later this week.

It is understood the woman, who has not been named, was on the first stop of a 60-day cruise around Australia, with tickets costing in the tens of thousands of dollars for the journey.

She had joined a group hike to the island's highest peak, Cook's Look, before she decided she needed to rest, according to the Courier Mail newspaper.

But she did not make it back to the ship, which then departed without her.

Incidents like this are rare, and cruise ships have systems to record which passengers are embarking or disembarking, Harriet Mallinson, cruise editor of travel website Sailawaze told the BBC.

"Sneaking ashore or [back] onboard just isn't an option," she said.

Cruise lines take these procedures very seriously and have "clever tech in place to prevent such incidents from happening. This is most likely a shocking - and tragic - one-off", Ms Mallinson added.

A satellite map of Lizard Island, located off the coast of Queensland, Australia. The map highlights a hiking trail in yellow leading to Cook’s Look summit, marked with a white dot near the island’s centre. A label indicates where the Coral cruise ship was moored offshore to the northwest of the island. Surrounding the island are turquoise waters and coral reefs.

Traci Ayris was sailing near the island last weekend and told the Australian Broadcasting Corporation (ABC) that she saw a helicopter using a spotlight to search a walking trail on the island at around midnight on Saturday.

She said about seven people with torches went to the island to search but it was called off at around 03:00 on Sunday (18:00 GMT Saturday) with a helicopter returning on Sunday morning when the body was apparently found.

"We knew she was dead because they called everyone back from the search immediately," she told ABC.

"And no-one went to the spot that the chopper was hovering over until later that day when the police arrived."

A spokesperson for Amsa said it was first alerted to the missing woman at around 21:00 on Saturday by the ship's captain.

The authority said it would work with other relevant agencies to investigate the case and that it takes the safety of passengers and crew onboard commercial vessels seriously.

Ms Ayris also said the incident was clearly distressing for crew and passengers.

"It was very sad in this paradise to have this tragedy occur. It should have been a happy time for that lovely lady."

A report into the "sudden and non-suspicious death" of the woman will be prepared for the coroner, Queensland police said.

The incident happened on the first stop of a 60-day trip around Australia

Coral Expeditions chief executive Mark Fifield said staff had contacted the woman's family and were offering support over the "tragic death".

"While investigations into the incident are continuing, we are deeply sorry that this has occurred and are offering our full support to the woman's family," Mr Fifield said.

"We are working closely with Queensland Police and other authorities to support their investigation. We are unable to comment further while this process is under way," he added.

The Coral Adventurer caters for up to 120 guests with 46 crew, according to the company's website. It was purpose-built to access remote areas of Australia's coast and is equipped with "tenders" – small boats used to take passengers on day excursions.

The vessel has continued its voyage to Darwin. (BBC, but headline rejigged)