A rock fisherman thought to be in his 70s has died after being pulled from the water at Narrabeen on Sydney's northern beaches.

Police and paramedics were called to the scene at Turimetta Headland at around 11am after the man was reported to have fallen into the water.

The man – who was wearing a life vest – drifted about 700 metres from the shore.

He was winched from the water by the Westpac Rescue Helicopter and flown to Rat Park in Warriewood.

NSW Ambulance paramedics performed CPR but the man could not be revived and died at the scene.

Speaking to 9News, beachgoer Steve Knight said today's big swells looked dangerous.

"The seas were really big today, there's a huge swell and I wouldn't be fishing in those conditions thats for sure," he said.

Local Jo Ayer said it was a risk many who enjoyed fishing on the rocks were known to take.

"They're obviously doing something they love right, and there's risks involved," she said.

Officers attached to the Northern Beaches Police Area Command will now prepare a report for the Coroner.