Sydney Festival is breaching its sustainable event policy with its attraction 'The Beach at the Cutaway' which is made up of more than a million plastic balls, environmental groups say.
Festival-goers have been invited to take a dip inside an art installation of 1.1 million plastic balls that "make up an ocean without sharks".
The groups said the balls posed a danger to the environment and they were disappointed the festival was promoting an installation that generated such a large and unnecessary impact on the environment.
Liza Dicks from Sea Shepherd's National Marine Debris Campaign said she was concerned beaches were already littered with too much plastic.
"I think it's an inappropriate message in this day and age - we are trying to put a message out that we need to reduce our plastic consumption," she said.
"(There are) 7 billion people on this planet and the amount of plastic that we are consuming every single day is not sustainable in any form.
"It's a very sad fact of life that we are producing this art installation for the festival when already our beaches are actually littered in plastic.
"We're trying to put a message out that we need to reduce our plastic consumption - our beaches, our oceans are choking with plastic.
"They (Sydney Festival) say they have a sustainable policy but I'm not sure you could call this sustainable, shipping seven containers of plastic balls around the world.
"They say it's going to be recycled, but it's still being manufactured in the first place, it still has a footprint and it's not a necessary art installation or a message that we need to be sending out there."
Paul Sharp from Two Hands Project said making Sydney Festival plastic-free would have been a better option.
"Sydney has a profound problem with plastic pollution. Our beaches are choking in plastic, our councils are spending millions of dollars every year trying to clean up the mess and to have a frivolous representation of a plastic beach," he said.
However Sydney Festival's artistic director Wesley Enoch said they were dealing with the plastic responsibly.
"We've been very thoughtful of the idea of reduce, recycle, reuse," he said.
"This project was only possible because the balls already exist as part of this art installation in America. So we made the choice to travel those balls to Australia rather than to re-make them."
"There's a chance for the recycling of those balls and also we're in negotiations for the last month or so about re-using the balls in the installation in another place."