Searches of the shoreline, in the water and from the air have failed to find any sign of the 25-year-old man who went missing while diving just 50 metres off the beach at Cable Bay on Thursday.
Police, who have named the missing man as Aucklander Rangi Roydon Tapu (who is also believed to have an address at Mangonui), downgraded the official search late on Friday, after spending the day scouring the rocky shoreline at either end of the beach, with support from Far North Land Search and Rescue volunteers, while four members of the police National Dive Squad, fresh from recovering the wreckage of a plane that crashed into Lake Taupo, searched the seabed with help from members of the Mangonui Fire Brigade.
Local police and family members are continuing shoreline searches.
The head of Northland police Search and Rescue, Senior Sergeant Cliff Metcalfe, said he had grave fears for Mr Tapu given that he had been diving close to shore and had still not shown up. He had gone out by himself while a friend watched from shore. When his dive buoy stopped moving the friend went out to investigate, finding the man's catch bag and spear gun tied to the buoy but no sign of the diver.
Police, family and members of the public carried out an extensive search on Thursday, supported by Coastguard, Ahipara Surf Rescue and the Kerikeri-based Coastguard aircraft. Family members found one of Mr Tapu's gloves on the beach overnight; the second was found when the official search resumed at first light on Friday.
The police dive squad arrived about 11am, first searching the area Mr Tapu had last been seen, then carrying out a systematic grid search of the wider area.
"He's an experienced diver, he's been diving here for the last four to five days without incident, and he was in three to five metres of water 50 metres offshore, so it's a real mystery what's happened," Senior Sergeant Metcalfe said.
The summer had already seen an exceptional number of drownings, many of which could have been avoided with simple precautions, he added.
"The fine weather means large numbers of people are on the water, but they're making the same basic mistakes, and paying for it with their lives," he said.
He urged swimmers to be aware of powerful rips on the west coast and boaties to always wear a life jacket and let someone know where they were going. Divers should not dive alone, or have someone watching all the time, and young children needed to be watched constantly.
"Take your eyes off them for a moment and they're gone," he said.
Meanwhile Parapara man Aaron Rewa Inch said he saw Mr Tapu standing on a rock while others on the beach called for him to come back. He sat down on the rocks then disappeared into the water and did not resurface.
"He didn't look right. He looked groggy," Mr Inch said, adding that a boat had been launched to begin searching within a matter of minutes.