United Airlines is adding service to Dubrovnik, Croatia (from Newark Liberty); Athens, Greece (from Washington Dulles); and Reykjavik, Iceland (from Chicago O’Hare)  this summer as those countries reopen to international visitors who are vaccinated or who provide negative tests for COVID-19. Patrick Quayle, vice president of international network and alliances, said that as countries around the world begin the process of reopening, travelers are eager to take a long-awaited getaway to new international destinations. He said the routes are “the latest example of how United is remaining nimble in rebuilding our network.” United’s Travel-Ready Center enables customers to upload their COVID-19 testing and vaccine documentation, and have it certified ahead of check-in so customers can get their boarding passes before getting to the airport. United said it is the only airline that does this seamlessly in its mobile app. The addition of these new routes reflects an increase in interest among United’s customers: In the last month, searches on United.com for flights to Croatia, Greece and Iceland were up 61%.