Former Greens leader Bob Brown has promised the biggest environmental protest in Australian history if Adani's $16.5 billion mega-mine goes ahead in central Queensland.
"It will put the Franklin (Dam) campaign in the shade," Mr Brown told reporters in Sydney on Saturday.
"If the prime minister doesn't stop this mine ... and it were to proceed, I'll be there with thousands of other Australians, to peacefully stop this outrage in our time."
Mr Brown was addressing the media after the Sea Shepherd's flagship vessel docked in Sydney Harbour for the weekend, as it travels up the country's east coast in protest against the controversial coal mine.
The organisation is inviting the public on board the M/Y Steve Irwin for tours this Saturday and Sunday, before it continues it's three-week voyage to Abbot Point coal terminal.
"Sea Shepherd, this fabulous organisation, has ridden here on a wave of public approval," Mr Brown said.
He called on Prime Minister Malcolm Turnbull to get rid of coal and "say thumbs down" to the Adani mine.
Mr Turnbull, who was greeted by three peaceful Adani protesters in Caboolture on Saturday, said Australia's energy mix would include coal "at least for a very long time".
"We need to ensure our energy is more affordable," Mr Turnbull told reporters.
"We've had so much ideology and idiocy in energy policy in years past that now is the opportunity with the national energy guarantee to have a truly technology-agnostic approach so that the technologies compete.
"They will succeed depending on which provides the most affordable power."
