WASHINGTON — An elderly passenger on a luxury cruise was discovered deceased after being inadvertently left on Lizard Island, marking one of the initial stops on a two-month voyage encircling Australia.

The 80-year-old woman, whose identity has not been disclosed, went missing on Saturday night. Crew members of the Coral Adventurer realized she had not reboarded the ship, prompting an urgent search by land and sea. Her body was found on the island the following day.

Queensland police, as reported by the Australian Broadcasting Corporation, categorized her demise as “sudden and non-suspicious.”

Earlier on Saturday, the Coral Adventurer had anchored at Lizard Island, a secluded location approximately 19 miles from Australia’s Queensland coast. The Coral Expeditions website highlights the island as offering diverse activities, including hiking, swimming, and snorkeling.

The BBC reported that the woman had been hiking with other passengers but is believed to have separated from the group to take a rest.

Authorities are now investigating how the woman went unaccounted for when the vessel departed without her. The Australian Maritime Safety Authority told CNN it would be investigating the incident, including reviewing “the circumstances surrounding why the passenger may not have been accounted for during boarding.”

The woman had boarded the cruise just one day earlier. The reported $50,000 voyage was scheduled to take passengers around Australia, eventually reaching Western Australia.

Coral Expeditions CEO Mark Fifield told CNN the company was “deeply sorry” for the incident and has been in contact with the woman’s family. “We will continue to offer support to them through this difficult process,” he said.

The ship is expected to arrive in Darwin on November 2, where its crew will be questioned by authorities.