How was passenger on cruise ship left behind?

The appeal of Lizard Island is its remoteness. Located on the Great Barrier Reef, 155 miles from Cairns in tropical north Queensland, the island is known for its snorkelling, with giant clams nestled amid the coral. It also has a scientific research station.

- Daisy Dumas

Tourists are mostly kept at bay by its inaccessibility and high accommodation prices.

But a week ago, on the west of the island, Suzanne Rees, a healthy and active 80-year-old, died alone.

She had possibly just watched her luxury cruise ship, the Coral Adventurer, sail away without her.

The keen bushwalker from Sydney had intended to hike to the island's summit, Cook's Look, with other passengers on the second day of their 60-day circumnavigation of Australia. But feeling the heat, she turned around early. She never made it off the island.

Authorities were not alerted until five hours after the Coral Adventurer left Lizard Island at 3.40pm local time. The next day, Sunday, Rees was found dead close to the walking trail.

How she died, and why her absence from the ship was not immediately flagged, are the questions being asked by her grieving family, other cruise passengers, industry experts and authorities.

Rees and her fellow passengers boarded Coral Expeditions' Coral Adventurer, which can carry 120 passengers and 46 crew, in Cairns on 24 October. Balcony rooms on the 93.4-metre (306ft) vessel were priced at A$86,400 (£43,000) a head, according to Clean Cruising.

VesselFinder satellite tracking data shows the ship left Cairns at about 5.30pm, arriving at Lizard Island at 8.30am on Saturday.

Rees was among a group of passengers who headed to the island to hike but, according to her daughter, Katherine Rees, she had cut her walk short.