The daughter and son-in-law of a grandmother who died after being deserted on an island by a luxury cruise ship believe she had been told by her tour guide to walk back to the boat alone.

Suzanne Rees, 81, was separated from a group hiking to the summit of remote Lizard Island, in the Great Barrier Reef, on October 25, 2025.

She had been part of a bushwalking group in Sydney and got an all-clear from her doctor before boarding the Coral Adventurer, operated by Coral Expeditions and owned by NRMA, for a 60-day luxury cruise at a cost of $30,000.

Despite her clean bill of health, the grandmother began feeling sick halfway through the hike on Lizard Island in baking midday temperatures - the boat's first stop. 

'It was a person on the hike who mentioned that my mum was feeling unwell - or not too good I think were the words - and apparently she was told to go back down to the boat,' Ms Rees' daughter, Kate Rees, told 60 Minutes on Sunday.

It's understood the tour guide sent Ms Rees to hike back to the boat, on a notoriously difficult trail, by herself.

The grandmother never made it to shore but nevertheless the ship left without her.

It took an astonishing five hours for the staff aboard the Coral Adventurer to realise Ms Rees hadn't returned to the ship. The alarm was raised when she failed to show for dinner.

Ms Rees's body was found 50m off the hiking trail on October 26, 2025 - the day after she disappeared. She died of heatstroke.

Kate believes the hot weather on the day of the hike should have seen staff on the cruise, which is marketed to retirees, call the walk off.

'My mum was capable. She walked all the time. And I think what should have happened if it was the conditions were unacceptable, the walk should have been cancelled in the first place,' Kate said.

'Somebody needed to make that decision and say, 'too hot, we're not doing a walk'.'

Kate and other members of Ms Rees' family have been left with many questions in the wake of her death which NRMA and Coral Expeditions have not answered.

The thought of her mother's final moments haunt Kate, she often thinks about how the 81-year-old would have felt completely abandoned while alone on the remote island.

'We did get contact from NRMA but by then I felt like we were a loose end that needed to be tidied up,' Kate said.

'It would be one of the most horrible ways to die. That does haunt me.'

In a statement to 60 Minutes, Coral Expeditions described Ms Rees' death as 'devastating' and said the company is 'deeply sorry'.

'While Coral Expeditions had comprehensive safety systems and procedures in place, we acknowledge some of these were not adequately implemented on this tragic day,' it said.

'Ms Rees' death has shocked our people to the core and we will continue to co-operate fully with the ongoing investigations.

'Coral Expeditions has introduced additional systems and procedures to further strengthen protections for our guests.'

NRMA similarly said it would 'continue to assist the authorities to determine exactly what happened in the lead up to this tragic event'.

'We recognise many questions remain unanswered, but we believe it is important to respect the investigation process,' it said.