There's been a dramatic rescue in Auckland after a woman drove off a wharf into the sea.

A member of the public alerted police shortly after 3pm that a woman driving a BMW had driven off Fisherman's Wharf at Northcote Point.

The man had seen what had happened and tried to get the woman out of the car before police arrived.

Police say the car was filling with water and the woman was drowning.

Officers who arrived at the scene managed to get her out by smashing a window.

She's been taken to North Shore Hospital with minor injuries.

It's not clear what led to the woman driving into the water.