The Evros Delta, in the south of the Evros regional unit, is located at the point where the waters of the river Evros flow into the Thracian Sea. During antiquity, it was known by the name of Ainisio Delta, after the ancient Thracian city of Ainos (nowadays Enez). Later on, during the Byzantine period, emperors used to hunt in the area. Ottomans used to call it Gyaur Anda, meaning 'the island of the Infidels'.

The materials transported by the river create many junctions forming lakes, lagoons, and islets in between; the rich vegetation affects the microclimate of the area.

Like most wetlands, the Evros Delta is an incredibly diverse and ecologically important ecosystem. Migratory birds from Northern Europe and Russia winter or pass through the Evros Delta on their journey to Africa and vice versa. Moreover, the excellent climate creates excellent conditions for the breeding of these species.

Over the years, various irrigation, as well as land drying projects that have been carried out, have changed the character of the area.

The Delta area is 200,000 hectares which are included in the list of protected areas of the international Ramsar Convention. Part of the Delta is designated as a Special Protection Zone and is proposed as a Site of Community Interest in the Natura 2000 network.

There are two large lagoons in the Delta: the Drana (or Lake of the Dragon) with an area of 6,000 acres and the Palukia with an area of 2,800 acres.