Relatives of the Marokopa family that went missing for 17 days have shed some light on the conditions they faced in a tent in dense bush while an extensive search and rescue operation was underway to find them.

Thomas Phillips and his three children, Jayda Jin, 8, Maverick, 6, and Ember, 5, who had not been seen since September 11, returned unharmed to a family farm on Thursday morning - despite friends and family fearing the worst.

Rozzi Pethybridge, Phillips' sister and the children's aunty, has told NZME of the shock of receiving a phone call to say they were safe.

The desperate search for the family started nearly three weeks ago after Phillips' ute was found below the high tide mark on Kiritehere Beach. The fear they could have been swept out to sea increased as the weeks passed.

Earlier on, the family had hope. "I think most families in this situation do hope and hope and hope."

But it seemed "pretty obvious that they had gone in the sea". Rescuers who specialised in rough sea conditions had given the family "some pretty grim facts".

Pethybridge said the "distinctly sad" family had been resigned to probably never seeing their loved ones again, and were braced for a four-to-six-week wait to find their bodies.

Thursday's phone call left her in disbelief. "Very very happy - but hard too after such a long time and being braced for the worst, resigning ourselves to the fact that we'd probably never see them again".

Being reunited was the best day of her life, she said. "Seeing them all again, being able to realise that and hold them in your arms and tell them all the things you thought of that you wanted to."

Pethybridge said it had been the first time she'd been able to smile or laugh in nearly three weeks without feeling sad. "You feel like your heart's whole again."

The children were perfectly healthy, which she put down to her brother's "awesome skills" as an outdoorsman. They had been in a warm, dry shelter - essentially "just on a camping trip with dad".

"That's down to Tom's awesome skills as a bushman and as an outdoorsman...he's got awesome survival skills and they didn't do it hard at all," she said.

"[They're] bouncing around having Milos and things with their cousins and colouring in and things - lovely happy little kids."

Pethybridge also gave heartfelt thanks to those who had helped in the search, from local iwi to LandSAR and fire crews.

"We are truly grateful, just very humbled by the support we've received."

Pethybridge took to Facebook on Thursday night to say she was "thankful beyond belief they are home safe".

It was the "best outcome after a long and harrowing ordeal".

"Glad you returned bro and I knew you would take care of your wee preciouses [sic]," she wrote.

"My heart feels bruised and weakened but is on the mend," she wrote.

Pethybridge also shared a song titled Hey Brother by Swedish DJ Avicci.

Police and emergency services - as well as hundreds of locals and volunteers - had spent days searching for the family in the area of Kiritehere and Marokopa.

Police suspended the search for the missing family last week, 12 days after they were last spotted.

Waitomo district mayor John Robertson said the community had gone through "a whole series of emotions" over the past three weeks.

At first, despite real concerns, people believed the four would be found. Phillips was a bushman who knew the environment well, so the community believed he had probably gone into the bush and was caring for the children well.

"But then you went from that sort of emotion to some anxiety as time went on - frustration as the search wasn't yielding any results, and then I guess the grief as the search then turned to focus on the ocean and the feeling was that there's a reasonable chance that they've been lost at sea."

That grief had turned to elation yesterday with a sense of relief and joy among locals.

"When you think all that happened over a two-and-a-half-week period, the community were all over the moon. They're just delighted to see Thomas and the three children surviving this."

He thanked everyone who had been involved in the search. Marokopa was a small, close community and the Phillips had been farming there for some time which added to the emotions people felt when they disappeared.

He didn't know the details of what had happened in the intervening days as police were still working through their investigation.

'17 days of hell'

A member of the public contacted police after sighting a man and three children on a bike early on Wednesday morning.

Police deployed a fixed-wing plane and drones to the area but the family were not found straight away.

All huts and bush areas were searched - but to no avail. After these extensive searches, Phillips and the three children turned up at the farm.

Police spent Thursday speaking with Philips to establish all the facts about what had occurred.

Inspector Will Loughrin, Waikato West Area Commander, said the family had "experienced 17 days of hell".

"To happen this way, is fantastic for the family. This is a family that experienced 17 days of hell, really."

Family members, including the three children's grandparents, were still processing what happened and trying to support one another, Loughrin said.

However, they were "ecstatic" the family had returned.

"We always held out hope that we'd be able to bring the family home alive."