United and Delta say they will offer daily flights to Iceland and Greece this summer, the first European destinations to open to vaccinated Americans

• United and Delta will offer seasonal daily service to Iceland and Greece this summer.
• Both countries heavily depend on tourism, and the EU is under pressure to reopen to travelers.
• International travel was down more than 75% in March compared with 2019, industry data showed.

US tourists eager to go abroad will be able to visit three European destinations this summer, so long as they can prove they are vaccinated against COVID-19.

On Monday, United Airlines said it would begin seasonal daily service to Iceland and Greece beginning in July.

United's move follows Delta Air Lines' announcement last month that it would offer daily service to Iceland from three US cities (via Boston Logan International Airport, Minneapolis-St. Paul International Airport, and New York's John F. Kennedy International Airport) beginning in May. And Delta's route map indicates flights from JFK to Athens, Greece, will resume in June.

United will also offer thrice-weekly routes to Croatia, which reflects an increase in search activity on its website over the past month, the company told Bloomberg. Each of the European routes are new for United and are as follows: Chicago to Reykjavik, Iceland, starting June 3; Washington, DC, to Athens, Greece, starting July 1; and Newark, New Jersey, to Dubrovnik, Croatia, starting July 8.

Iceland is part of the Schengen zone of visa-free travel but not a member of the European Union. Therefore, it is exempt from the general restriction on visitors from outside the EU. Iceland Air recently told international travelers that the country could not be used as a kind of backdoor to the continent, saying, "Further travel from Iceland to the rest of Europe is currently not permitted for non-Schengen residents."

Greece, meanwhile, just lifted its restrictions for travelers from the US who can provide a vaccination certificate or a negative COVID-19 test result. As an EU member, Greece's move puts additional pressure on the bloc to reopen travel more broadly.

Both Greece and Iceland are heavily dependent on tourism dollars. Tourism constitutes about one-tenth of Greece's economy, and those revenues plummeted 80% as a result of the pandemic, The National Herald reported. In 2019, tourism represented 42% of Iceland's economy, according to Statistics Iceland. In an attempt to incentivize visitors, Iceland Air is promoting round-trip prices as low as $350 and waiving change fees to give flyers greater flexibility when traveling.

Data from an industry trade group showed international travel was still down more than 75% in March compared with 2019.