Opponents of a $500 million wind farm in southern Hawke's Bay say the proposed site is geologically unstable and full of holes like Swiss cheese.
Three commissioners in Dannevirke are considering an application from Contact Energy to build a 65 turbine farm on the Puketoi Range, south-east of the town.
Contact Energy considers the 3500-hectare site as almost ideal and says the project is a key component of its $2 billion investment programme in renewable electricity generation.
But many families in the rural community of Waitahora, close to the proposed wind farm, say the land is full of holes and highly unstable.
More than 100 people have formed the Waitahora Puketoi Guardians Incorporated Society to fight the application.
Tania Simmons, who chairs the group, says residents are not opposed to wind energy, but the site is totally unsuitable.
Ms Simmons says Puketoi range contains a considerable amount of limestone. The land is riddled with large underground cavities, making it which unsuitable for turbines weighing hundreds of tonnes.
She says Contact Energy's failure to carry out a full geo-technical survey of the site seriously weakens the company's case and commissioners should reject the application.
Ms Simmons says there is also major opposition to the wind farm because it would ruin what is regarded as an outstanding natural landscape of national importance.