Waiwera Thermal Resort is under fire for its new policy of banning people from bringing their own food and drink.
The country's largest thermal pools resort, 35km north of Auckland, announced the crackdown on February 1, saying it was "based on usual international practice".
The resort, which is now Russian-owned, stated on its website that it aimed to keep grounds cleaner and more hygienic.
Food and beverages would be confined to its cafe, kiosk or designated outdoor areas.
Barbecues and pre-booked parties could still be "self-catered" at areas further away from the pools.
However, the move was yesterday denounced as a "purely money-making decision" that contradicted a Kiwi tradition of taking a picnic to the pools.
Mike Whybro, of Albany, started a "protest against the pools" campaign on Facebook last Friday and said the site had already drawn nearly 400 followers.
"There seems to be a groundswell of protest from average people - Kiwi families - who feel the same," said Mr Whybro.
His circle of family and friends had regularly enjoyed the outdoors at the pools.
"Now, given that a family pass is $65 and adult $26 already, and their food within the resort is extremely expensive - mostly deep-fried rubbish and very limited in terms of variety and healthy eating - we feel strongly that this is just another step in the wrong direction and effectively price gouging and greed," said Mr Whybro.
Since 1875, commercial bathing facilities have operated at Waiwera and the complex claims 350,000 visitors a year.
The Herald reported in September that Mikhail Khimich, a Moscow entrepreneur and rugby fan, had bought the Waiwera resort.
During the Rugby World Cup, his gleaming 48m ketch Thalia was berthed near the Viaduct Harbour for his stay.
A rebranding campaign aims to turn Waiwera into a premium water brand worldwide and focuses on its Kiwi heritage.
Both Waiwera's nearest competitors - Parakai Springs, near Helensville, and Miranda Hot Springs - let patrons bring a picnic.
Yesterday, in a park next to the Waiwera complex, the Herald found the Moses family from Mt Roskill preparing to cook meat on a portable barbecue.
Abdul Moses, his wife, Hanifa, and their sons Mushtaq and Mosheen had left relatives swimming at the complex in order to have the meal ready.
"We are Muslims and this is halal meat which we cannot get at the pools," said Mr Moses.
"So, we have always brought our own food for a picnic when we come here - three or four times a year. But you pay enough money to get into the place without having to hire their barbecue at $30 an hour.
"How can people living on a wage go in there if they have to buy their food or pay for barbecue?" asked Mr Moses, a bus driver, who has visited Waiwera pools for 25 years.
Herald inquiries were referred to the email address of a company employee but no response had been received last night.