Authorities say a rescue mission by an Australian icebreaker remains on track as it closes in on a ship wedged in sea ice near Antarctica.
A group of scientists, explorers and tourists has been stuck on the Russian research ship MV Akademik Shokalskiy about 1500 nautical miles south of Hobart for the past five days.
Although the expedition's leader says spirits are high among those on the ship, a retired Brisbane teacher aboard as a tourist says frustration is building.
Two icebreakers have given up on efforts to push through the thick and dangerous ice floes near Antarctica to try to free the trapped research vessel.
A third icebreaker, Australia's Aurora Australis, is on its way to the stranded ship and is due to arrive about 1am New Zealand time on Monday.
It is the last ship in the area that will be able to help.
The Australian Maritime Safety Authority (AMSA) says Aurora Australis is about 85 nautical miles from the trapped ship.
"The Aurora Australis remains on track to arrive in the vicinity around 11pm AEDT," an AMSA spokeswoman said in a statement.
If the icebreaker can't battle through the ice, AMSA says a second option may be to consider ferrying trapped passengers with a helicopter.
The locked-in ship, with 74 people on board, including several New Zealanders, sent a distress call on Christmas Day after becoming trapped in heavy sea ice.
The ship had been undertaking the Spirit of Mawson voyage, which is retracing Sir Douglas Mawson's Antarctic expedition.
Professor Chris Turney of the University of NSW is leading the expedition, consisting of scientists, explorers and enthusiasts undertaking climate research.
He has insisted that everyone is in good spirits despite the ordeal during several interviews with international media outlets.
"Morale is remarkably high," he told CNN.
But a level of anxiety among some passengers is beginning to emerge as they, too, are able to send word home.
Retired teacher Kayleen Lawson, of Brisbane, is onboard the stricken vessel after paying thousands to join the expedition as a tourist.
"The frustration is not knowing when we're getting out of here, when we're going to go home," Lawson told News Corp during a satellite phone interview.
"It was meant to be the trip of a lifetime, and it still is ... but it's turning out a little differently to what I expected."
She said the ship is now surrounded by ice at least three metres thick.
The Aurora icebreaker is rated at being able to push through ice slightly deeper than one metre thick.
China's Snow Dragon icebreaker, which came within six-and-a-half nautical miles of the stuck ship before turning back out of safety fears, is standing by in case its helicopter will be needed.
An expedition tracker and blog can be found at spiritofmawson.com.