Tasmania has extended its border closure with southeast Queensland until at least 4pm on Sunday, mirroring the mainland state's lockdown.
The Queensland government on Monday lengthened the lockdown for 11 areas after 13 new locally acquired cases of the highly infectious Delta coronavirus strain were recorded.
"I understand this is an inconvenience but I want to stress this is a very serious situation," Tasmanian Premier Peter Gutwein said.
"The Delta variant is a whole new ball game."
Tasmania shut with southeast Queensland on Saturday and has told some 11,000 recent arrivals to stay home.
Anyone in Tasmania who has been in the region since July 17 must stay home for 14 days from when they arrived and return a negative test before being allowed out.
People can leave their homes, provided they wear a mask, for grocery shopping, medical care, to get tested, exercise and work or study.
Police cautioned four Queensland tourists who tried to enter Cradle Mountain National Park despite being subject to the directive.
A 19-year-old Tasmanian woman who recently returned from southeast Queensland was also warned after attending the Hobart waterfront on Saturday night.
"I understand there have been a number of other reports of people that haven't been abiding by the stay-at-home order. They may not be so lucky. There is a $774 on-the-spot fine," Mr Gutwein said.
"The reason we're asking you to stay at home is so you can keep our community safe."
Tasmania, which hasn't had a community case since May last year, is also closed to NSW and designated high-risk premises in Victoria and South Australia.
The island state on Friday opened up Pfizer vaccinations to people aged 30-39 and has since registered some 10,000 bookings in the cohort.
The government has put a call out for enrolled nurses to join the vaccination effort.
Australian Associated Press