Crew members aboard the Pacific Explorer reported the passenger missing at about midnight, when the ship was around 70 kilometers (43 miles) out to sea from Cape Jaffa in South Australia state.
The Australian Maritime Safety Authority then launched a rescue plane overnight that was joined by two helicopters at daybreak. Searchers said they found the unnamed woman’s body in the water just before 7 a.m.
The cruise ship, which can accommodate some 2,000 guests, left Melbourne on Tuesday bound for Kangaroo Island in South Australia on a four-night return voyage.
Cruise ship company Carnival Australia said it was a tragic outcome.
“We continue to provide care and assistance to the family member this guest was traveling with and extend our deepest condolences to their loved ones,” the company said in a statement.
Carnival Australia said the death also “deeply impacted” other guests and the crew.
“We thank all involved who supported this distressing and challenging search operation,” the company said.
South Australia police said the ship’s intended visit to Kangaroo Island was canceled and that Victoria Police would conduct an investigation into the circumstances surrounding the death.
Weather conditions overnight were “extremely poor” with strong winds and big seas, Dan Gillis, a duty manager with the safety authority, told the Australian Broadcasting Corp.
Gillis said the woman’s body was taken to Adelaide by helicopter, after it had earlier been taken to a nearby hospital for identification.