A handful of pilot whales stranded off Tasmania's remote west coast have been freed but the massive rescue effort will take days.
About a third of the 270-strong pod, which got stuck on sandbars at Macquarie Harbor on Monday, have already died.
Rescue efforts to refloat the mammals began early on Tuesday morning, with the wet weather and area's unique tides making the operation tricky.
"We have now freed a small number successfully that appear to have stayed out at sea and are now scaling up that approach," state Parks and Wildlife manager Nic Deka said on Tuesday afternoon.
Marine Conservation Program wildlife biologist Kris Carlyon earlier said progress would be slow, with the day's efforts a "critical phase".
"Basically we'll take the animals with the best chance to start with and the ones that we are able to deal with," he told reporters.
"Some animals may be simply too big or in an unsuitable location."
Mr Carlyon said about one-third of the whales had died as of Monday evening and most were inaccessible by boat.
"In terms of mass strandings in Tasmania, this is the trickiest we've had to deal with," he said, adding the mission could take days.
About 60 people are helping with the rescue, including 40 parks and wildlife staff and personnel from nearby fish farms, which have supplied boats.
Members of the public are being urged to stay away from the high-risk operation.
The whales are spread across two sandbars, while 30 stuck on a beach have died.
Mr Carlyon said pilot whales were a robust species and the survivors had a chance of lasting several days if the weather stayed cool.
"It's ugly for people on the ground but as far as the whales go, it's ideal," he said.
The whales got into trouble on Monday morning but the rescue couldn't begin until marine specialists were able to survey the scene.
It is understood to be the biggest mass stranding in Tasmania in more than a decade.
The social pilot whales, which travel in groups of up to 1000, could have been drawn close to the coast to feed or because the pod followed the misadventure of a few individuals, Mr Carlyon said.
