The United States Coast Guard will resume searching for an Australian man at first light after he went overboard from a cruise ship on-route to Hawaii.
A Coast Guard crew in a HC-130 Hercules aircraft spent six hours looking for the man in the area about 800 kilometres south of Kailua-Kona, Big Island.
He had been aboard the Quantum of the Seas ship that departed Brisbane for the Hawaiian islands on April 12.
"Joint Rescue Coordination Centre Honolulu received a report from the cruise ship Quantum of the Seas of a man overboard at 11.03pm Tuesday evening (Wednesday night AEST)," the Coast Guard said in a statement on Thursday.
"The crew of the cruise ship remained on scene to search for approximately two hours, deploying six life rings."
The Hercules aircrew arrived on scene at approximately 9am and has since returned to refuel before resuming at first light.
Cruise operator Royal Caribbean confirmed the guest had gone overboard on the trans-Pacific leg of the journey.
"The ship's crew immediately launched a search and rescue operation and is working closely with local authorities," a spokeswoman said.
Cruise ship passenger Georgina Thompson told Channel 9's Today show she heard repeated calls of "Oscar" over the PA system.
Oscar is used as an emergency code onboard cruise ships.
"There were lights … shining on the ocean and also there were a couple of boats out there in the water," she said.
"The light started searching along the outside of the ship.
"You just knew that something was wrong. My husband thought we might have hit something."
Guests had earlier commemorated Anzac Day with a Dawn Service on board.
The ship is scheduled to arrive in Honolulu on Friday.