Rough conditions are hampering the search for a woman who fell overboard from the cruise ship Pacific Dawn.
A crew member saw the woman fall over the side of the ship about 4pm AEST, 150 nautical miles west of New Caledonia, the ship's owner P&O said.
"A crew member notified the bridge straight away and the 'man overboard' incident response was activated immediately," spokesman David Jones said in a statement.
"In line with this response, Pacific Dawn turned around to follow the course it was on at the time of the incident."
The Australian Maritime Safety Authority and New Caledonian authorities have issued a call for nearby vessels to assist in the search.
A passenger, who requested not to be named, described the atmosphere on the ship as "very sad, solemn and quiet".
A Brisbane man holidaying on the ship with his family, who also requested not to be identified, told AAP conditions in the search area are rough, with 3-to-4 metre swells.
He said little information was being given to passengers about the situation other than they were searching for the missing woman.
An AMSA spokeswoman described the conditions as "poor", saying there were 30-knot winds and it was pitch black.
Another passenger, Jonathan Trevithick, posted an image on Twitter of a life ring floating in the water and said the situation was "horrendous".
He told AAP the captain had announced the search would continue until midnight.
The ship was on a week-long cruise of Pacific islands, leaving Brisbane last Saturday.