Trained rescuers with the Tasmanian Marine Conservation Program managed to escort 25 whales back out to sea on Tuesday but say the rescue will take several more days as numerous whales are in "relatively inaccessible" locations, per the BBC.
The challenge will be what to do with those animals once they are refloated.
"We're dealing with large, distressed animals, for several days at a time, and it does take an emotional toll sometimes", said Kris Carlyon, a biologist with the state government.
Mass whale strandings off Tasmania's coast are not uncommon, with researchers labelling the state as a "global hotspot" for strandings, ABC News reported. About 30 whales were on a beach, 200 were on a sandbar, and a few dozen more were farther out in the water.
About 60 people are helping with the rescue, including 40 parks and wildlife staff and personnel from nearby fish farms, which have supplied boats.
Authorities do not know why the whales became stranded.
"They are in water, but it's very hard to see how many of those whales are deceased or what condition they're in", he told reporters Strahan, a town in Tasmania.
However, she said the whales were "in good hands", describing the Tasmanian team as experienced and saying a stranding event of this scale was "just impossible" to predict. "It's very hard to see how many might be deceased or what condition they're in", said Nic Deka, an incident official with the Tasmanian Department of Primary Industry, Parks, Water, and Environment.
Drawing them back out to sea is a labour intensive process that can include physically pushing the animals or using specialised tarpaulins and pontoons to drag them to deeper water.
According to NPR, Tasmania has more whale strandings than any other Australian state, and Macquarie Harbour, where the pilot whales are now, is one of the most common stranding sites.
These mass strandings often involve social species that live together in large groups, according to the department. The government scientist who first saw the mass stranding from air estimated only 70 whales, however, the number of whales appeared to be much bigger. They wore wetsuits and were working in shifts to prevent hypothermia.
The poor weather, however, could help the partially submerged whales survive for the several days the rescue is likely to take, Carlyon said.