An 80-year-old woman was found dead after being left behind by a cruise ship having disembarked on a remote island.

According to the The Guardian, Suzanne Rees, of New South Wales, had joined a hiking party on the island with some other passengers. When it came time to get back on the Coral Adventurer cruise, however, she wasn’t among them.

Lizard Island, on the Great Barrier Reef, was the first stop in the 60-day cruise around Australia. The Guardian reports balcony room tickets for the cruise itself cost around $86,400 per person.

While Rees’ death is being treated as ‘sudden and non-suspicious’, her family believe the cruise company failed in their duty of care. Rees’ daughter Katherine said she was “shocked and saddened” that her mother had been left behind, describing the events that led to the tragedy.

Speaking to The Australian, Katherine said: “From the little we have been told, it seems that there was a failure of care and common sense. We understand from the police that it was a very hot day, and Mum fell ill on the hill climb. She was asked to head down, unescorted.

“Then the ship left, apparently without doing a passenger count. At some stage in that sequence, or shortly after, Mum died, alone.

“I hope that the coronial inquiry will find out what the company should have done that might have saved Mum’s life.”

As per Queensland Police, Coral Adventurer, a 306-feet long ship with a capacity of 120 passengers and 48 crew members, raised the alarm over Rees’ disappearance on Saturday, October 25.

A rescue helicopter was launched at 12:45 a.m. the following morning, with Rees’ body found later that day, October 26.

“We are currently investigating the circumstances surrounding why the passenger may not have been accounted for during boarding,” said a spokesman for the Australian Maritime Safety Authority’s emergency hotline.

In a statement earlier this week, Mark Fifield, the Coral Expeditions’ chief executive, acknowledged the “tragic death of a passenger on the Coral Adventurer during an excursion to Lizard Island”.

“A search and rescue operation was launched on land and sea,” he said. “Following the operation, Coral Expeditions was notified by Queensland police that the woman had been found deceased on Lizard Island.

“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.”