Surf Life Saving New Zealand says two men were caught in a rip at Onemana Beach on Thursday afternoon and one has died.
It said the two men were believed to be swimming north of a patrolled area on the Coromandel Peninsula, when they got into difficulty just before 3pm.
Surf Life Saving NZ said the incident happened outside the flagged area but a lifeguard managed to swim out to the two men and bring them ashore, where he began CPR on one of them.
The lifeguard was joined by three other lifeguards and CPR was carried out for 15 minutes until an ambulance arrived.
One of the men died at the scene, Surf Life Saving New Zealand said.
"Our thoughts are with the man's family and friends at this time."
The death has been referred to the Coroner.
Surf Life Saving NZ said its team would work with emergency services to establish the circumstances of the incident.
It follows on from yesterday's two incidents in which people died in the water.
One person in Northland couldn't be revived after being found unresponsive in the water at Kai Iwi Lakes.
Another person, a crab fisherman, was also found dead after getting into difficulty at Uretiti in Northland.