The Balearic Islands, Malta, the Portuguese archipelago of Madeira and Barbados are among the places added to the green list for travellers from the UK.
Transport secretary, Grant Shapps, confirmed people entering the UK from these destinations will not have to quarantine from 04:00 on Wednesday.
Shapps also confirmed there were plans to allow quarantine-free travel from amber list countries for people who were fully vaccinated.
However, the prospect of European holidays could face another hurdle after German chancellor, Angela Merkel, earlier suggested all EU countries should make British travellers quarantine on arrival to slow the spread of the Delta variant.
Also added to the green list are Anguilla, Antigua & Barbuda, the Balearic Islands (which include Ibiza, Menorca, Majorca and Formentera), Bermuda, British Virgin Islands, Cayman Islands, Dominica, Grenada, Montserrat and Turks & Caicos Islands.
The full list can be seen here.
Following the news, Javier Piñanes, director of the Spanish Tourist Office, said: “We are delighted that the Balearic Islands has been added to the UK’s green list for travel meaning that British travellers will be able to visit the archipelago without the requirement of quarantine on their return to the UK.
“This development illustrates the excellent progress that has been made in the archipelago regarding Covid-19 and is a step forward for both the Spanish and British travel industries.
“We hope that the rest of Spain will be added to the list very soon so that British residents can once again enjoy their holidays in Spain and/or be reunited with relatives.”
Six destinations have also been added to the red list today - Dominican Republic, Eritrea, Haiti, Mongolia, Tunisia and Uganda.
Those travelling to the UK from these countries will need to quarantine in a hotel for ten days on arrival.
The department for transport said it was intended that later in the summer arrivals who were fully vaccinated would not have to quarantine when travelling from amber list countries.
Officials said this change was expected to take place in phases, starting with UK residents.
The department also said it intended to remove the guidance that people should not travel to amber countries, and it would take clinical advice on whether regular testing could provide a safe alternative to quarantine for children accompanied by vaccinated adults.
Shapps added: “We are moving forward with efforts to safely reopen international travel this summer, and thanks to the success of our vaccination programme, we are now able to consider removing the quarantine period for fully-vaccinated UK arrivals from amber countries - showing a real sign of progress.”
Rory Boland, Which? Travel editor, said: “The addition of more holiday destinations to the green list will be welcomed by holidaymakers and industry alike, but travellers still need to be extremely cautious about booking trips this summer, even to green list destinations.
“Countries can be downgraded quickly and with little warning, as we saw with Portugal, while several European countries have introduced quarantine requirements for UK residents.”
He added: “Restrictions around international travel are changing regularly and when they do, the cost to holidaymakers is significant.
“Most providers will not pay refunds if a country is moved from green to amber, and ‘free’ amendments are often anything but, with many companies requiring significant notice of any changes and bookings for new dates usually costing hundreds of pounds.
“Travel insurance is also unlikely to pay out in these circumstances.
“It is only advisable to book if you are able to do 14 days quarantine, can be flexible about destination and dates, and book with a provider that guarantees refunds in the event of traffic light changes or quarantine requirements.”