The main access road, the Arthur Highway, remained closed. Police and commercial boats were being used to ferry in supplies and ferry out people most in need.
Prime Minister Julia Gillard said the federal government was supporting the fire effort.
"We are working with the state government to support people and make sure that they get through," Ms Gillard told ABC radio.
"My message is there's only one you.
"Everything else in life at the end of the day, no matter how precious, can be replaced.
"What can't be replaced is a human life."
Insurers declared the bushfire-hit towns a catastrophe and police powers were increased when the Tasman Peninsula was declared a serious-incident site.
The Insurance Industry Council of Australia's declaration included the towns of Dunalley, Connellys Marsh, Forcett, Copping, Murdunna, Boomer Bay, Primrose Sands, Susans Bay, Eaglehawk Neck and Taranna.
Electricity company Aurora told people whose power had been cut off to expect delays of several weeks before it was restored. About 300 poles were down on the Tasman Peninsula.
Property losses from the peninsula fire have been huge, with 30 per cent of the buildings in the small community of Dunalley, 55km southeast of Hobart, destroyed. These included the school, police station and bakery.
At Connellys Marsh, 40 per cent of the buildings are gone, including three houses at Copping and several at Primrose Sands.
Twenty houses have been lost around Murdunna.
Several thousand people, many of them tourists, are stranded with access roads closed.
Around 700 are taking refuge at the Port Arthur historic site, another 2000 at a community centre at Nubeena and more than 50 at the Dunalley pub.
Up to 1000 people were reported to have been rescued from beaches by boat overnight, but police could not confirm the number.
They said boats had ferried in 3000 meals as well as fuel, water and medical assistance.
"Where we possibly could, we were moving people out by vessel overnight," Acting Commissioner Scott Tilyard told reporters on Saturday.
"The vast majority of people still remain down there."
No deaths or serious injuries have been confirmed.
A fire in the Derwent Valley northwest of Hobart was affecting the communities of Ellendale and Karanja, but the extent of property damage was unknown.
Conditions across southern Tasmania on Saturday were cooler than on Friday, when Hobart reached 41.8C - its hottest since record keeping began in 1883.
State fire chief Mike Brown said similar conditions in 1967 had resulted in the loss of 2000 homes and 62 lives.
"I would imagine there'll be numerous stories about the heroic and risky approaches that were taken out there," he said.
"The big outcome for us ... is that at the moment there looks to be no loss of life or injuries."
He said this was because of the way "we put out our warnings, and clearly a lot of people did heed those warnings".
-AAP
