People travelling to the UK from Canada and Denmark will not need to isolate as the UK's latest Covid travel rules have come into force.
Finland, Switzerland, the Azores, Liechtenstein and Lithuania are also on the "green list" as of 04:00 BST.
Travellers from newly red-listed Thailand and Montenegro now need to isolate in government-approved hotels.
All arrivals must take at least one Covid test - but many countries have banned UK residents from entering.
Travellers coming from green list countries do not need to quarantine when they come back to the UK - whether or not they have had two doses of a coronavirus vaccine.
They still have to be tested before their return to the UK, however, and book a test for day two after their return, and fill in a passenger location form.
Only British or Irish nationals and UK residents are allowed into the country if they have been to red list countries. They then have to pay to self-isolate in a government-approved quarantine hotel.
Most countries are on the amber list - fully-vaccinated adults do not have to quarantine on their return from these locations, but do have to have tests before returning and two days after they get back.
Those who have not had both vaccines have to isolate at home for 10 days, as well as having Covid tests.
The travel industry has criticised the UK's changing travel rules, with airlines saying the system risked making international travel "more expensive, burdensome and uncertain compared to other countries".
Travel lists are currently updated every three weeks and the system is similar for England, Scotland, Wales and Northern Ireland.