There were fears a woman would drown as she was swept three quarters of a mile down the River Usk towards the sea yesterday morning.
Fire rescue staff had to pursued her along the river and described saving her at the "last possible moment" while eyewitness Dario Oliver thought she would die as she frantically struggled to stay above water.
Mr Oliver was staying at a friend's flat in Devonia House, Rodney Road, Newport, when he heard "a commotion, sirens and people shouting" at 1am.
He looked out to see the woman, in her early 20s, being carried on the water at a quick pace between the Newport University building and George Street Bridge.
The 21-year-old said: "She was being taken out to sea with firemen on the banks trying to keep a track on her with torches and chucking life rings out. I honestly thought she was going to die, she kept going under the water and splashing."
He said: "My stomach was turning, it was horrible", as he watched the tide wash her back out to the middle of the river every time she got close to the side.
The film editor added: "The pace she was travelling was scary, I was sure she would be taken to sea. But, fair play to the firemen, they followed her all the way."
Crews from Maindee and the specially-trained Malpas technical rescue station were called by the police, with Malpas station manager Shaun Moody describing it as a "rapidly developing situation".
The woman had fallen into the river near the Millennium Bridge, with 20 firefighters having to negotiate thick mud on the banks and launch a small inflatable boat near George Street Bridge.
Mr Moody said: "She had gone down under the water a couple of times, it was touch and go, but we were able to get to her at the last possible minute before she was washed out to sea."
The crew pulled her on board and took her to shore, where they used stretchers and an inflatable walkway to get her up the mud banks.
She was taken to Newport's Royal Gwent Hospital, suffering from exhaustion and mild hypothermia.
Mr Moody warned locals about the dangers of walking near the banks of the River Usk in Newport during high tide.
The technical rescue station has sent its boat out seven times in the last three months to rescue people.