The “paddle out” is surfing’s most hallowed ritual, a floating memorial ceremony in which mourners join hands and reminisce at sea.

On Sunday, surfers paddled out from Australia’s most famous beach, but this time it was not to remember one of their own.

Instead, they were calling attention to a stretch of rich, pristine ocean that they say faces a mortal threat from a plan to open it to natural gas and oil drilling.

The gathering, on Bondi Beach in Sydney, was part of a series of protests that have gathered force in recent weeks across Australia in an effort to protect the Great Australian Bight, a haven for some of the world’s most unusual marine life.

The proposal by the Norwegian company Equinor to drill in the waters off Australia’s southern coast has galvanized surfers, including generations of the sport’s most famous professionals here.

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Surfing holds great economic, social and cultural significance in Australia, which has some of the world’s most beautiful, unspoiled coastlines.

“Today is the day we draw a line in the sand,” said Damien Cole, a surfer who led the paddle out from Bondi’s shore.

“We’re in the midst of a climate emergency, and here’s a company working with our federal government to go into one of the most remote and pristine ecosystems, risking everything.”

As federal elections approach on 18 May, the Equinor proposal is becoming a test of whether Australia is more committed to extraction of natural resources or protection of unspoiled ecosystems, with beaches as a political forum.

Many Australians are already frustrated with the government’s failure to curb carbon emissions.

Other environmental issues have also roiled the nation’s politics, including a mining giant’s recent announcement that it will push ahead with a huge coal project and a political scandal, known as “watergate”, relating to costly water licenses.

The first such event to raise alarms about the Great Australian Bight was held this month at Bells Beach, a renowned surfing spot southwest of Melbourne, and it drew thousands of people.

Events on the Gold Coast and in Tasmania have attracted thousands more.

“I haven’t seen anything like this before,” said Layne Beachley, a former world champion Australian surfer, referring to the scale of the paddle-out protests.

“To see so many surfers standing up and using their voice and position to let the people in power know we’re vehemently against this proposal is really powerful,” Beachley said.

The Bight has been called Australia’s answer to the Galápagos: a stretch of ocean facing the Antarctic that is home to calving whales and teeming fisheries.

The Bight’s marine environment is starting to be recognised by scientists as part of a “Great Southern Reef” that rivals the Great Barrier Reef for ecological value.

But experts say the Bight also holds one of the world’s great remaining natural gas reserves, and Equinor, a company controlled by the Norwegian government that was once known as Statoil, plans to begin drilling by the end of this year.

Equinor changed its name to move away from the word “oil” as it stresses investments in renewable energy.

The plan to extract natural gas still requires approval by Australia’s offshore oil and gas drilling regulator, and Equinor insists that exploration will be safe.

In Australia, the fossil fuel industry has a long history of political connections.

And candidates who support the proposal argue that opening the Bight to drilling would create jobs and wealth for decades to come in the struggling post-industrial area of South Australia.

But many people fear that the Bight, much of which extends along the state of South Australia, could face catastrophic damage in the event of an oil spill.

Last month, Equinor made public its environmental plan, which experts said showed that a major oil spill in the Bight could cause environmental damage along several thousand miles of the southern Australia coast.

This escalated local concerns, particularly because the Bight’s waters – which are deep, rough and remote – pose an even greater challenge to drilling than those of the Gulf of Mexico, where the Deepwater Horizon oil spill, considered the industry’s worst, occurred in 2010.

Adding to the worries was a report this month by an international petroleum law expert, Tina Soliman Hunter, which concluded that Equinor’s proposal was too risky given the remote location, harsh environment and lack of surrounding support infrastructure to deal with an accident.

It also faulted Australian regulations for preventing and responding to an oil spill, saying they are less stringent and such drilling would not be permitted under Norwegian law.

“Equinor is proposing a lesser standard for the Bight than they would propose in the Norwegian Sea,” said Ms Soliman Hunter, of the Aberdeen University Centre for Energy Law.

In Norway, by contrast, the opposition Labour Party withdrew support this month for oil drilling in the country’s Lofoten Islands, considered an Arctic wonder, creating a significant barrier to exploiting the area.

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Those waters are believed to hold significant oil reserves, and the decision represented a drastic shift in policy on fossil fuels, an industry that has made Norway one of the world’s most affluent countries.

Surfers who oppose drilling in the Bight plan to take their message to Norway next month by paddling out and protesting in front of the Oslo Opera House.

In the meantime, they are calling for the Bight to be listed as a World Heritage site.

And surfing’s biggest names – like Mick Fanning, a three-time world champion, and Steph Gilmore, a seven-time world champion – have pleaded in an open letter for the Bight to be kept free of drilling.

“An oil spill in the Bight would be catastrophic,” they wrote in the letter last month, adding: “The Bight is wild and pristine and should remain that way.”