Government scientists said about 90 of the 270-strong pod of pilot whales have died since they were spotted from the air in shallow water off the rugged coastline on Monday.
Footage showed large numbers of the animals prone on a wide sandbar at Macquarie Harbour, about 200 kms (120 miles) northwest of the state capital Hobart, while others floundered in slightly deeper water.
Rescuers save lives
Rescuers had to get in the icy water to attach the whales, a species of oceanic dolphin that grow to 7 metres (23 ft) long and can weigh up to 3 tonnes, to slings and then guide the animals as boats dragged them out to deeper water.
"We settled on a method where we get a sling placed under the whale, that's attached to a boat (and) we also have crew in the water," said Nic Deka, a regional manager of Tasmania's Parks and Wildlife Service, at a news conference.
Rescue efforts on!
More than 60 people are involved in the rescue effort, including local fishermen and volunteers. They wore wetsuits and were working in shifts to prevent hypothermia.
Why do whales beach?
Scientists do not know why whales, which travel together in pods, sometimes beach themselves but they are known to follow a leader, as well as gather around an injured or distressed whale.
Pilot whales are a species of oceanic dolphin that grows 7 metres (23 ft) long and can weigh up to 3 tonnes.