The proposed East Antarctic marine park would protect one million square kilometres of ocean, but has repeatedly been struck down at meetings of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), which began Monday.
China and Russia have been key in blocking the proposal, which was first floated by Australia, France and the European Union in 2010 before being scaled down in 2017 in an attempt to win greater support.
All 26 members of the organisation must consent to the marine park's creation, and the proposal is now back before the CCAMLR as it convenes in Australia's southernmost city, Hobart, for two weeks of meetings on Antarctic conservation.
It has previously established other major ocean Antarctic sanctuaries -- including the world's largest spanning 1.55 million square kilometres in the Ross Sea -- but governments and environmental groups say more action is needed to protect the last pristine continent.
Australian Environment Minister Sussan Ley said in a statement ahead of the meeting that the east Antarctic proposal would protect the area's "distinctive deep-water reefs and feeding areas for marine mammals".
Cassandra Brooks, an assistant professor of environmental studies at the University of Colorado, told AFP the threat posed by climate change to the Antarctic -- and by extension to humans -- meant urgent action to protect the area was required.
"There is so much definitive evidence now about climate change. About climate change effecting the poles, the ocean," she said.
Daniel Bray, a senior politics lecturer at La Trobe University, said any chance of the marine park being approved would likely require a shift in position from China -- which hopes to keep open the possibility of fishing in the area.
"China is really crucial to getting this over the line," he told AFP.
"I think if China can come on board then Russia would be isolated and probably there would be a lot of pressure for them to agree as well or at least be a little more forthcoming about why they're opposing, because while they couch it in scientific terms it is generally for political reasons."
The CCAMLR is also considering two other marine park proposals, in the Weddell Sea and the Antarctic Peninsula.
If all three were to go ahead, it would protect more than 7 million square kilometres of ocean in the Antarctic, including existing sanctuaries.
But Bray said "frustration was building" over whether the CCAMLR can deliver the proposed network of marine parks due to failures at past meetings, casting doubt on their ability to reach consensus at the latest round.
A decision is expected to be made public at the conclusion of the meetings on November 1.