The cutouts were planted by Greenpeace to send a message to the nation's leaders to choose the Great Barrier Reef over the coal industry, Greenpeace Australia Pacific campaigner Nikola Casule said.

A sign that said "choose the reef, not coal" was also on display.

The act was in response to new research undertaken by ReachTEL for Greenpeace Australia Pacific that showed more than two-thirds of Australians want the government to prioritise the Australian environment over the coal mining industry.

"Almost a quarter of the reef's coral died this year," Mr Casule said.

"Australia can't have both a healthy Great Barrier Reef and a coal industry."

Greenpeace representatives will hand over a petition with 30,000 signatures to new energy and environment minister Josh Frydenberg on Wednesday morning.

The petition urges the government to commit to a halt of new coal mine approvals and a plan to phase out existing coal mines in Australia.

"We hope that by bringing the Great Barrier Reef to Canberra, politicians will be able to see first-hand what is at risk from their unwavering support for the coal mining industry," Mr Casule said.

"Australia's coal mining industry exports more than one billion tonnes of carbon emissions each year. This contributes to increasing ocean temperatures which are killing the reef," he added.