Emergency services responded to the Auckland beach community about 11.45am, police said.
Three off-duty surf lifeguards from the Piha Surf Life Saving Club responded to the incident.
They deployed an inflatable rescue boat (IRB) in swells of 2 metres, a spokeswoman for Surf Life Saving said. She referred further questions to police.
The witness, who regularly surfs at the beach, said seeing rescuers try to resuscitate the person “does throw you for the day. It stays in your mind”.
“There were a whole lot of people sitting at the scene there, at Mermaid Pool around the corner, near the Keyhole.
“They were taking turns giving the person chest compressions. They must have been doing that for about 10 minutes.
“And then everyone turned around and came back to the main beach. In the back of the IRB, the body was obviously in there because as they were driving they were doing compressions with the person in the boat.
“As they were doing that the Westpac Helicopter came overheard. The IRB and the lifeguards went to the lifeguard tower there, and the helicopter landed.”
He said police cordoned off the carpark and main road.
