A man working on the hull of the PS Waimarie jumped into the Whanganui River yesterday to save a woman who threw herself off Dublin Street Bridge.
Shaun Pirere took the plunge after seeing the woman plunge into the water.
A police spokeswoman said there were multiple calls to Whanganui Police when the woman was seen sitting on the side of bridge at 11.15am yesterday morning.
"There was obvious concern for her safety," the spokeswoman said.
Police were there soon after, but were unable to prevent the woman jumping into the water on the eastern side of the river.
John Turnbull was working near the bridge and said the first he knew of the incident was turning around to see his workmate Shaun Pirere dripping wet and talking to police.
Mr Turnbull said Mr Pirere told him he'd seen the woman jump, hold on to the bridge pylon for a bit, then let go.
"He said she floated for about 20 seconds, then went under."
That was when Mr Pirere took action, swimming to the middle of the river and hauling the woman back to shore.
"She would have been a goner if it hadn't been for Shaun," Mr Turnbull said.
The woman was taken by police to Whanganui Hospital where she was checked by medical staff, and found to be uninjured.