A cruise passenger was found dead after she didn't return to her ship in Australia, according to police and multiple news reports.

The guest died on Lizard Island on Oct. 26, the Queensland Police Service told USA TODAY. "The woman was reported missing to the police after failing to board a vessel in waters off Queensland on Saturday October 25," police said in an emailed statement.

Lizard Island is located on the Great Barrier Reef.

Her death was "sudden and non-suspicious," authorities said. Her family identified her as 80-year-old Suzanne Rees, according to The Guardian.

"We understand from the police that it was a very hot day, and Mum felt ill on the hill climb," her daughter, Katherine Rees, said in a statement. "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."

The woman had been sailing with Coral Expeditions aboard the Coral Adventurer ship, CNN reported. The company’s CEO, Mark Fifield, told the outlet that a search by "land and sea" took place after the passenger was discovered to be missing.

"The Coral team have been in contact with the woman’s family, and we will continue to offer support to them through this difficult process," Fifield said in a statement, according to CNN.

The Australian Maritime Safety Authority (AMSA) told USA TODAY that it "will make an assessment as to whether there was any non-compliance associated with the passenger not being counted onto the ship and, if necessary, will take action to address them." The safety regulator will conduct inquiries on the ship when it arrives in Darwin, though details on timing were not available.

"We are currently investigating the circumstances surrounding why the passenger may not have been accounted for during boarding," AMSA added in an emailed statement. "As the matter remains under active investigation by AMSA, no further details can be provided at this time."

The vessel had reportedly just begun a two-month cruise around Australia. Coral Expeditions did not immediately respond to USA TODAY’s requests for comment.

Police said a report will be prepared for the coroner, and did not have further details to share.

This story has been updated to add new information.

Nathan Diller is a consumer travel reporter for USA TODAY based in Nashville. You can reach him at ndiller@usatoday.com.

This article originally appeared on USA TODAY: Cruise passenger found dead after she didn't return to ship in Australia

Reporting by Nathan Diller, USA TODAY / USA TODAY

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