Te Uri chairman Rawson Wright said the land deal was very significant for the hapu, which had fought to develop its 616ha coastal forest property and was delighted with the outcome.
"In order to develop the parts of the forest being retained, we are gifting 196ha to Auckland Council to create a wonderful conservation and recreation resource for Auckland," Mr Wright said.
The 10km stretch of unspoilt beachfront land in the 196ha block runs from the Department of Conservation's Mangawhai Wildlife Refuge at Mangawhai Harbour to Te Arai Pt, which the council owns.
The Te Arai Coastal Lands Trust - the partnership between the hapu and Queenstown-headquartered Mr Darby - said the estate was about the same size as Cornwall Park and on prime coastal land.
The land, worth $5-10 million, is intersected by the Te Arai Stream and includes the Mangawhai North Forest, beach frontage, wetlands and dunes, the trust said.
Auckland councillor Chris Darby said the 196ha was a sizeable addition to the regional parks network and fortuitously comes while the council's budgets are stretched.
"It was previously identified by council as a high priority for acquisition with prime conservation and recreation values. The land also abuts the Hauraki Gulf Marine Park.
Watch: John Darby talks new projects
"It offers future horse-riding trails and walking tracks and provides for the long-term protection of a remarkable coastal landscape.
"The acquisition puts a once remote and private paradise on New Zealand's coastline within reach of all Aucklanders," Chris Darby said.
Mace Ward, the council's regional and specialist parks manager, said people already visited and rode horses on the 196ha but the new park would not be completed for years.
"The parkland vesting will occur following the subdivision consenting process for the 43 houses.
"All going well, this is two to three years away.
"A lot of the management will be focused on protecting the fairy terns at the mouth of the stream," Mr Ward said.
What's what at Te Arai
• Golf course: almost finished by American financier Ric Kayne.
• 43 houses: planned by millionaire Queenstown developer John Darby.
• 196ha conservation park: vested in Auckland Council, works planned for next 2-3 years.
• Outcome: links two existing reserves to create more than 500ha of public land.