It lies at about 120m below the surface, between the Mokohinau and Hen and Chicken Islands, just inside the Auckland coastal marine area but also under the watch of Northland Regional Council.
Turner said the diver had been following a line and when it appeared he was in trouble the dive buddy had tried to help but was unsuccessful.
Coastguard northern region duty officer Nico Doodeman said on the night of the incident, a rescue helicopter and two Coastguard vessels were called out to the scene.
They searched the area until they were stood down about midnight, he said.
The search was resumed at first light on Monday and involved a search from the air as well as on the water.
"But there's been no sign of him," Doodeman said.
All on-water searches have been suspended and the Wellington-based police dive squad will be called north when sea conditions become calmer.
Turner said when a weather window opened, which might be on Sunday, the dive squad would start their search. He said Navy and Customs would also be called into help with the operation.
"We are supporting the man's family at this difficult time," he said.
The suspected drowning brings the number of water fatalities in Northland to four this year - two have been divers.
On January 27 a diver in his 50s died when he did not resurface off the coast of Taiharuru.
Water Safety New Zealand chief executive Jonty Mills said diving was becoming increasingly popular and people needed to take the necessary safety precautions.
"People young and old are diving and they need to make sure they have the appropriate training. They also have to make sure they have gear that is fit for purpose," Mills said.
Being familiar with the sea conditions was also key and if it was not suitable for diving then "don't go".
In Northland he said diving was closely linked with "getting a feed for the family" but divers needed to be prepared and know their own limits.
If they had health niggles they should not be diving.
