Auckland leaders have begun expressing strong opinions about the proposal to build a new stadium on the city's waterfront at the Ports of Auckland.
The Chamber of Commerce has called the plan "exciting", while a senior councillor has spoken out against the scheme.
An engineer who specialises in underwater developments has panned the project as an impractical, unrealistic and "incredibly expensive" dream.
Sorry to pour water on the fire, but seriously, I think these guys are dreamers. Get real. Build it on the land for a third the price
The proposal is to build a $1.8 billion stadium alongside Bledisloe Wharf. Its top would be level with Quay St, at about 4.5m above the king tide level, and its base would be 28m below sea level - 10m of it in seawater, and a further 18m into the seabed.
"Sinking the stadium into the seabed eliminates most of the contentious, costly and complex aesthetic and engineering issues of an above-ground stadium and is very do-able from an engineering perspective," said Dave Wigmore, the chairman of the consortium behind the scheme.
The consortium says the stadium would be built at no cost to ratepayers and taxpayers.
It would be funded by the consortium being given the rights to build housing on 9ha at Eden Park and develop Bledisloe Wharf with apartments, commercial buildings and public space.
Auckland Council planning committee chairman Chris Darby opposes the new scheme.
Darby, the councillor for North Shore, said Auckland did not need a new or totally refurbished stadium any time soon. It would probably need a totally refurbished stadium in the 2030s.
The Bledisloe Wharf proposal was a distraction, he said on social media. The "true contenders" were a new city-centre stadium located east of Spark Arena or a refurbished Eden Park. Further work was needed in evaluating those options.
He said he was "not seduced by the promise of a free, gifted stadium on the waterfront … There will always be hooks to the 'free stadium' suggestion, with value transfer from cashing up Eden Park being the first conditional hook".
Darby declared himself not excited by the possibility of "crowding out the Waitematā's glistening edge with the enormous footprint of a stadium".
Auckland Chamber of Commerce chief executive Michael Barnett said the idea of the stadium was "exciting" and now was the time to celebrate the creative minds and "dreamers" behind the design.
"I think anybody that has a vision that looks at Auckland and looks to enhance what we are doing and where we are going is a great thing."
"When you have a good idea, you have to put good visual in front of people. Then everything is open for debate."
Later would come the hard questions about the true cost of operating and paying for the facility.
"The other discussion you want to have, is that you don't want to build the stadium before looking to have events; we need to have a range of events that can easily transfer into the venue."
Although initial plans said there would be no funding from taxpayers and ratepayers, it would be "inevitable" that they would end up forking out some cash.
"It's inevitable that we will. We need to have a compelling story behind it.
"There will be operational costs and, unless people of Auckland want a substantial bill, we need to have a pipeline of events.
"There will be employment and some great returns for the city on the other hand. If it is going to take 10 years what about Ports of Auckland? They don't have anywhere to go."
Engineer Mike Murphy, who has specialised in the design and construction of large public aquariums and other underwater structures, said: "It's nice to dream."
"However, in the real world, the practicalities of building a huge stadium submerged 28m below sea level are huge, and incredibly expensive," he added.
The scheme posed enormous problems in waterproofing and safe anchoring.
"... how long will the rock anchors last before they corrode? Very sceptical they will last 50 years."
Murphy questioned how such a huge expanse of concrete, which always cracked and had many construction joints, could be waterproofed to resist 28m of water pressure.
"Sorry to pour water on the fire, but seriously, I think these guys are dreamers. Get real. Build it on the land for a third the price."
The Stop Stealing Our Harbour group said its preference, instead of the new stadium plan, was for the development of a long-term strategic plan that encompassed the entire waterfront, one that included what would happen after the port operations had been shifted elsewhere.
"Until we have a workable long-term waterfront plan, the existing waterfront infrastructure should be utilised in the most efficient way to cater for Auckland's needs without any ad hoc incursions on the Waitemata Harbour," said spokesman Michael Goldwater.
"Any major infrastructure assets like a stadium must be considered in light of a waterfront masterplan Aucklanders are still waiting for. Until a post-port waterfront plan has been completed, talk of where a central-city stadium should go is premature."