A rescue ship sent to help an ice-trapped Russian liner with New Zealanders on board is close to its target with only 20 nautical miles (37 kilometres) between it and the the stranded ship.
But the Chinese icebreaker Snow Dragon may not be able to reach the stranded vessel if the ice is too thick and the ship's master determines the trip would not be safe.
About 50 tourists, scientists and explorers and 20 crew are on the Russian ship MV Akademik Shokalskiy, which became trapped in heavy sea-ice near Antarctica and sent a distress call on Christmas Day.
Four New Zealanders - ornithologist Kerry-Jayne Wilson, a former Lincoln University lecturer who now lives on the West Coast, paramedic Colin Tan and two caterers, including Central Otago woman Nicole Kerr from Omakau - are also on board.
Three ice-breaking ships were sent to assist the stranded vessel in the remote location more than 1500 nautical miles south of Hobart.
Earlier this evening, China's Snow Dragon vessel was within 20 nautical miles (37 kilometres) of the MV Akademik Shokalskiy.
Australian Maritime Safety Authority (AMSA) spokeswoman Andrea Hayward-Maher said the vessel would assess the ice to see if it could reach the stranded ship.
"This could be a very lengthy process as it depends on the thickness of the ice," she said.
"The masters will have to determine whether it's safe to get to the Shokalskiy and if they have the capability to do that."
If the Chinese vessel, or the French icebreaker L'Astrolabe not far behind it, cannot reach the trapped ship, a third rescue vessel, Australian Antarctic Division vessel Aurora Australis, may have a better chance.
Ms Hayward-Maher said the Aurora Australis had a betting rating in terms of ice-breaking.
Other options included bringing in ice-crushing vessels or using aerial assets in an emergency, she added.
said while the Snow Dragon was close, there was a 20 kilometre ice edge between him and the ship.
"A long way from where we first got locked in the sea ice," he said in a video posted on the Intrepid Science website today.
Professor Turney said the weather had improved and the ship was no longer in a blizzard.
The ship is being used for the Spirit of Mawson voyage, which is retracing Sir Douglas Mawson's Antarctic expedition.