Lynda Newnam is concerned proposed new wharves at Kurnell and La Perouse could dramatically change the face of the region's iconic beaches.
The La Perouse resident said the Kamay Ferry Wharf proposal was ill-conceived and could negatively impact beachgoers and the environment.
Sutherland Shire Council has also voiced concerns about the lack of parking at Kurnell and called for a dedicated area where passengers can leave their cars.
Ms Newnam said that families often ventured to the beach at La Perouse due to its low-cost appeal.
"There are four hours of free parking... residents and business owners fought against paid parking," she said.
"So people come down, they can park their car and they can enjoy their day on the beach where the big indulgence might be some fish and chips or even a Mr Whippy.
"The ferry could cost people $60 per family - $60 for a family to sit on a diesel polluting ferry is hardly sustainable compared to a swim and a walk in the bush and beach followed by fish and chips at one of the local cafes."
The NSW Government plan includes a 180-metre wharf at La Perouse and a 230-metre wharf at Kurnell.
These wharves will be able to cater for ferries up to 40 metres long and smaller recreational vessels.
The plan has been met with mixed reviews from residents, environmentalists and the Department of Primary Industries (DPIE).
The DPIE has raised concerns about the lack of information available about vessel routes and types and the impact the plan could have on popular fishing grounds in the region.
Ms Newnam said people visiting either Kurnell or La Perouse generally only spent the day exploring one of those regions.
"If you come to La Perouse, you are generally only spending four or five hours here - not everyone has eight hours to spend out here, especially if they are coming from elsewhere," she said.
"The big attractions at Kurnell are the Whale Watching at Cape Solander and then the low-impact diving, snorkelling and fishing.
"A ferry to La Perouse doesn't add to this, particularly interfering with container shipping.
"Parking at La Perouse is restricted to four hours, so how much time is there to do La Perouse and Kurnell?"
The government has already set aside $16 million for the Kamay Ferry Wharf project, which, if approved, is expected to be completed in 2022.
However, Ms Newnam is concerned about the impact the plan could have on the environment in the bay, including seagrass.
"We've lost so much seagrass already," she said.
"Seagrasses support a lot of marine life. But, unfortunately, the Environmental Impact Statement also doesn't acknowledge the New Zealand Fur Seals that come through there.
"It also didn't acknowledge the diving or snorkelling that people enjoy."
Sutherland Shire Council, in its submission to the environmental impact statement, supported the plan but raised concerns about parking at Kurnell and the impact more vessel movement could have on sea grass in the bay.
"The proposal will impact significant seagrasses including 682m2 of Posidonia australis, which is listed as an Endangered Community under the Environment Protection and Biodiversity Conservation Act (EPBC Act) and is an endangered population under the Fisheries Management Act," the council's submission stated.
"This seagrass also provides potential habitat to the endangered 'Whites Seahorse'. Therefore, the council does not support the impact of this sensitive area of seagrass.
"There is insufficient information presented regarding the currently unspecified mitigation and offset plans to minimise the impact to this community/population."