Ninety Mile Beach forms the cornerstone of a $120 million Treaty deal which is being signed today between five Far North iwi.

The iwi, who have 40,000 members and are part of the Te Hiku Forum, are Ngati Kuri, Te Aupouri, Ngai Takoto, Te Rarawa and Ngati Kahu.

Iwi leaders will gather at Ahipara to sign the agreement in principle which deals with the tribes' "shared" or overlapping interests.

A co-governance entity for the beach, known as the Te Oneroa a Tohe Statutory Board, will be established.

Made up of Crown and iwi representatives, the board will develop a management plan and will work on regeneration of toheroa and other fauna and flora on the beach.

Crown income from tourist buses that traverse the sands will be directed to the board to fund its projects.

Once the agreement is legislated in a deed of settlement, the Crown and Te Hiku iwi intend to enter into a social accord under which the groups will meet annually to set objectives for better social outcomes.

One source said no one was quite sure at present what that would look like or how it would work.

Commercial redress includes $120 million between the Te Hiku iwi, transfer of the Aupouri Forest, and seven farms which the iwi will have to purchase for $25 million.

The Weekend Herald understands last-minute meetings were held yesterday to make sure the deal went ahead - one of the sticking points is between Te Aupouri and Ngati Kuri, who both claim Te Rerenga Wairua (Cape Reinga) as their own.

To deal with the iconic peninsula, the Crown has offered to vest 75ha in a historic reserve in "whichever iwi the Te Hiku Forum deem appropriate".

After nearly a quarter of a century of legal wrangling and stop-start Crown negotiations, there is a sense of exhaustion among leaders, tribal sources say.

Treaty Negotiations Minister Christopher Finlayson said the agreement would provide economic development for iwi and the region and better conservation management of sites.