A teenage boy has saved the life of a drowning woman by jumping 20 metres from a bridge into a freezing river on the New South Wales North Coast.

Fourteen year old Corey Warburton struggled for an hour to get the woman to safety, and managed to save the 70-year-old woman from death.

"I wasn't really afraid of what I was doing. I wasn't really feeling any emotion," Corey told Channel 7 News. "I just wanted to get the lady to safety."

Corey was on his way to a skate park, when he found a suicide note, clothes and glasses on the Grafton Bridge. He looked down and saw the woman's body floating in the river.

With no-one else around and no mobile phone, he jumped 20 metres into the water.

He then swam in the freezing water with the woman for half an hour while she drifted in and out of consciousness.

Corey then pulled her into the reeds where police and another teen helped drag them onto the bank. Corey's mother says, "It's not out of character for Corey. Corey has done stuff like that since he was tiny."

The woman is in a stable condition in hospital.