“When she went over [her husband] collapsed." The woman still missing from cruise ship.

It’s the story that left Australia stunned.

A 47-year-old Brisbane woman onboard P&O’s Pacific Dawn cruise ship fell overboard on Thursday, around the coastline of New Caledonia, and despite an extensive search, she still has not been found.

With the cruise ship now making its way back to Brisbane, a witness to the horrifying incident has stepped forward, offering new details on what happened.

According to the witness, who has asked to remain anonymous, the victim was on deck with her husband, when she fell ill.

She walked over to a railing to vomit over the side of the ship, and that’s when she lost her footing and fell overboard.

"[She was] vomiting outside, near the table tennis area," the witness told The Courier Mail.

"Leaning over, not far over, then she fell. When she went over [her husband] collapsed."

The incident happened at around 4pm on Thursday, and after being alerted to the incident, the ship then proceeded to circle around the area for hours trying to locate the missing woman.

After being unsuccessful, the search was eventually called off at 7.30am on Friday morning.

According to a P&O spokesperson, experts had told them "survival after this length of time in difficult sea conditions and after a full night at sea was not considered possible".

The captain made the difficult announcement to the other passengers onboard the cruise liner.

"It is with a very heavy heart that I need to let you know that we have been unable to locate our guest," the captain said.

"We are still in the area of the incident, and the weather conditions with the swell three to four metres high, as you can see outside… the strong wind made our search extremely challenging."

LISTEN: Laurie Lawrence’s water safety tips. Post continues below.

The woman was believed to have been travelling with her husband and children.

In a letter to guests onboard the ship, it was revealed the victim's family is being looked after by "special care trained crew", as they make the heartbreaking journey back home without their loved one.

Another passenger said staff had told them it's "not easy" to fall overboard, as the ship's railings are quite high.

The incident is not being treated as suspicious at this time.