The Russian research ship Akademik Shokalskiy and Chinese icebreaker Xue Long have broken free from Antarctic ice where they had been stranded for several days.
The Russian ship's captain said a crack had appeared in the ice after a change in wind direction.
The Akademik Shokalskiy got stuck on 25 December. It has a Russian crew of 22.
On Thursday, the Xue Long's helicopter ferried 52 passengers from the stranded Russian ship to an Australian vessel.
The Xue Long then became stuck itself on Friday.
"We're going slowly and zig-zagging, we've already moved more than 20 [nautical] miles," Captain Igor Kiselyov of the Russian ship told Itar-Tass news agency.
"It's tough going so far, a lot of mist, visibility is no more than 500 metres," he said.
He confirmed that the Chinese ship was also moving and that Akademik Shokalskiy was just north of it.
"It may catch up with us - in that case, we'll follow in its wake. But if not, we'll get out together, independently," he said.
A US Coastguard icebreaker, Polar Star, is heading towards the two ships, responding to an earlier request for help. It left Sydney, Australia, on Sunday and will take a week to get there.
The Akademik Shokalskiy got trapped by thick floes of ice driven by strong winds about 1,500 nautical miles south of Hobart in Tasmania. It was being used by the Australasian Antarctic Expedition (AAE) 2013 to follow the route explorer Douglas Mawson travelled a century ago.