A pianist employed on a Royal Caribbean cruise ship is expected to survive after two fishermen from Newport Beach, California, found him treading water in the Pacific Ocean nearly 20 miles (32km) from shore on Friday.

The man, whose identity has not been released, was taken to a hospital following the rescue, according to the US Coast Guard, which has opened an investigation into how he ended up overboard.

Authorities believe the crew member may have been in the ocean for about nine hours before he was spotted by Sean Norton and Grant Garrett, who were on their way back from a fishing trip near Catalina Island. The pair had spent the morning fishing for marlin, and by noon they had hauled the stranded man onto their boat.

Recalling the moment the boat's captain first caught sight of the man in the water, Garrett told CBS News: 'Yeah, it's a human being. Stop the boat; let's get all of our lines in.'

The fishermen worked together to bring the man onboard. Once he had regained his composure, he told them he was a pianist on the Ovation of the Seas, Royal Caribbean's 14-deck cruise ship. Norton said the exhausted crew member had little to say about the ordeal. 'The only thing he said to me was, Thank you. I thought I was gonna die,' Norton said.

After pulling the man from the water, the fishing crew sent out an emergency maritime call, and Newport Beach lifeguards responded to assist. Battalion chief Adam Yacenda said the man was located roughly 15 to 20 miles offshore, which he described to CBS as 'pretty much in the middle of the ocean.'

Norton said unusually warm ocean temperatures likely made the difference between life and death, pointing to what he called a 'crazy super El Niño year.' He noted the man was probably in the water for close to 10 hours, but said the water temperature was 76 degrees. 'A different year, no way he makes it,' Norton said.

The Coast Guard said the circumstances of the crew member's fall from the ship remain under investigation. Royal Caribbean Group confirmed the incident and said it is supporting its employee.

In a statement to CBS, a company spokesperson said: 'We are providing support and assistance to our crew member during this difficult time. To respect the privacy of our employee, we have no additional details to share.'