A body has been located in the water near Opoutere Beach, north of Whangamatā.

Police were alerted about 1.30pm, following the discovery by a member of the public near Slipper Island/Whakahau.

"While formal identification has yet to take place, Police believe the body is likely that of a swimmer who went missing on Wednesday January 18," says a police spokesperson.

A family of seven were swimming at Opoutere beach, north of Whangamatā on Wednesday morning.

Police and emergency services were alerted to a group of people in trouble in the water at 11.25am and a mass rescue operation took place.

At the time of the ordeal six members of the family were pulled from the water.

A person believed to be the father was pulled from the water but could not be revived despite crews doing CPR, says Fire and Emergency group manager Shane Bromley.

The 15-year-old family member who was still missing is the son of the deceased.

The death of the person located today will be referred to the Coroner.

Police say the search and rescue operation has now concluded.

"Police would like to thank all those involved in this operation including our partner agencies, Surf Life Saving New Zealand, NZ Coastguard, LandSAR, FENZ, and the Royal New Zealand Navy," says a police spokesperson.

Police are unable to release any further information at this time.