The relaxed requirements for entry to Greece will apply to those with a vaccination certificate or a negative PCR test up to 72 hours before arrival. PCR, or polymerase chain reaction, makes up the bulk of coronavirus testing.
Delta is operating more than 40 international routes from Atlanta, including to Mexico and the Caribbean, but has a more limited schedule to Europe with routes to Amsterdam, Paris, Frankfurt, London Heathrow and Rome.
A European entry ban bars many people from traveling to the European Union unless they fall under certain exemptions, while travelers to the UK must self isolate for at least 10 days after arriving.
Delta will fly both routes to Athens on 293-seat Airbus A330 jets.
Last month, Delta announced it would launch flights from New York, Boston and Minneapolis to Reykjavik, Iceland in May for vaccinated travelers. Iceland has exempted fully vaccinated travelers from testing and quarantine.
Iceland and Greece may attract travelers who are looking for international destinations with outdoor activities for tourists, and where their travel plans are not affected by quarantine requirements.