Opponents of Waiheke's first marina development have failed in the Supreme Court, confirming the project's legality and allowing work to continue as planned.

A spokesperson for the new 186-berth Kennedy Point Marina said the court decision was out and SKP (Inc) had not won.

In the last fortnight, issues arose about the penguin habitat at the site and those for and against the project met to try to iron out issues.

SKP, financially backed by Mainfreight founder and chairman Bruce Plested, has been fighting plans by Kennedy Point Boatharbour, which wants to build the marina at the car ferry terminal in a project proposed by developer Tony Mair.

A decision released today by the Supreme Court has again rejected a legal bid to appeal the consent granted for construction.

Opposition group, Save Kennedy Point (SKP), lodged an application to the Supreme Court in December to bring another appeal.

The High Court, Court of Appeal and now the Supreme Court, have all refused to allow SKP to challenge a decision of the Environment Court, rejecting its bid to have its 2018 appeal against the Marina heard again.

Kennedy Point Marina, Director, Kitt Littlejohn said; "The company is pleased to have received the Supreme Court ruling in its favour today. However, its main focus continues to be around bringing its vision for Kennedy Point Marina to life for the benefit of everyone within the Waiheke community, not just boaties."

The Supreme Court agreed that SKP's proposed appeal did not raise any legal questions of general or public importance.

It also found there was no miscarriage of justice because the Ngāti Paoa Trust Board had an opportunity to make a submission when the application was publicly notified, but didn't, and SKP had not produced any evidence of adverse cultural effects arising from the project. The court also found that there were no exceptional or circumstances warranting a further legal challenge.

In accordance with application requirements, the developer had consulted with Ngati Paoa and other mana whenua as required by Auckland Council and provided detailed cultural values assessments from Ngati Paoa and Ngai Tai ki Tamaki which assessed the marina development as appropriate from a cultural perspective, the business said.

Tony Mair, project director, confirmed that the company will continue to consult with mana whenua on building and its future operation in accordance with its mana whenua engagement plan.

Mair thanked the many Waiheke residents who had reached out to the Kennedy Point Marina team over the last six months with messages of support.

In 2016, the marina business won consent to develop the project but that was appealed unsuccessfully in the Environment Court by opponents.

SKP then went to the High Court to have that rejection overturned but they were late filing their appeal and although they sought leave to extend that period, they lost.

At the same time as that application was going on, they tried to go back to the Environment Court for a rehearing on the basis that there had been new and important evidence, or there had been a change in circumstance, which justified the new hearing.

That was heard in 2019 by the Environment Court, which rejected the opponents' case.

So SKP appealed that at the High Court. That matter was heard in June last year but the High Court said there were no errors of law by the Environment Court.

But the opponents again filed an application to appeal that High Court decision to the Court of Appeal. That was rejected late last year. The judges said they made their decision because the High Court's ruling was well-reasoned and cogent.

So SKP appealed the decision to the Supreme Court, hoping for a substantive hearing. That was rejected.

A few weeks ago, Mair's business began the construction of the project.

That includes widening the road accessway to what is now the car ferry at Kennedy Point.