It's a project that has riled the normally sedate residents of Manly and could soon see them marching in the streets.

The thought of losing their downtown car park – a long-time target of developers – and gaining a 740-space car park underneath Manly Oval at a cost of $35 million has locals in a lather and split Manly Council along party lines.

Potential carpark: Manly Oval as it currently stands. Credit:Peter Rae

Virtually all of Manly's precinct committees are opposing the project, which is part of council's Manly 2015 plan. It's being championed by Manly's Liberal mayor Jean Hay as a way to rejuvenate the area because it would enable the 1970s above-ground car park in the the centre of Manly to be sold for as much as $16 million.

The main objection is the financial risk that the project entails, North Harbour Precinct chairman Terry le Roux says. The project would involve council taking $35 million in borrowings over the next 50 years.