A man’s body has been pulled from the water after a desperate early morning search for a passenger who went overboard as a P&O cruise ship approached Sydney before dawn.

Water police battled rough seas on Monday looking for the man, who went overboard as Pacific Adventure sailed about 10 nautical miles south-south-east of Sydney Harbour.

More than six hours later, officers from NSW Police’s Marine Area Command retrieved a man’s body from the water.

P&O said its vessel had been cleared to return to port following the search, about 18 kilometres outside Sydney Harbour.

“We thank guests for their care, understanding and patience on what’s been a distressing day for guests and crew,” a company spokeswoman said.

She said the family of the dead man was “being cared for by our onboard team”.

Marine Area Command head Joe McNulty earlier said swells of up to five metres meant authorities had to rely on heat-seeking technology to find the passenger.

The search area spanned about 60 square nautical miles of water, he said.

The search was led by police and involved Pacific Adventure and nearby cruise ships.

Authorities had hoped to find the missing man alive, given a life ring from Pacific Adventure was yet to be recovered.

Passengers described the atmosphere on board the ship as tense and sombre as the search went on.

One passenger aboard the nearby Carnival Splendor, which was also involved in the search, shared a video of the rough conditions at sea.

“We have been offshore since about 4 o’clock this morning unable to dock due to an emergency situation,” she said.

“We are witnessing the helicopter searching and search and rescue boats as well … it is as you can see, quite choppy.”

Pacific Adventure was due to dock at Sydney’s White Bay Cruise Terminal inside the harbour early on Monday after a three-day Elvis-themed cruise off the NSW coast.

A P&O spokesperson said later in the morning the ship had been cleared to dock.

“Our thoughts are with the family of the guest at this difficult time,” the spokesperson said.

Pacific Adventure’s next scheduled departure, for a four-day trip to Queensland, has been delayed until Monday night.

An investigation has been launched into the incident and a report will be prepared for the coroner.

-with AAP