The two countries reached an agreement late last year to join the continent’s free-travel area by air and sea after Austria opposed full membership, including land crossings, arguing that Romania and Bulgaria need to do more to prevent irregular migration.

Under the agreement, after March 31 travellers from Bulgaria and Romania arriving by air or sea to other Schengen zone countries will no longer have to show passports upon arrival. But travelers arriving by train, bus, or car will still need to carry ID as rules governing land borders have not yet been established, due to a veto exercised by Austria out of fear of an influx of asylum seekers.

Despite the partial membership, lifting controls at air and sea ports is a great success after a 13-year wait.

“Schengen is not a physical fence along the border. It is first and foremost about trust, because we can protect the EU's borders, both the external border between the EU and Turkey and the borders at airports, seaports, and border gates. Partially joining Schengen makes Bulgaria confident to move forward on the European path," said Bulgarian Prime Minister Nikolai Denkov. 

With Bulgaria and Romania, the Schengen zone now includes 29 countries – 25 of the 27 European Union members plus Switzerland, Norway, Iceland, and Liechtenstein.