The Atanasovsko Lake is one of the Burgas lakes. It lies north of the town and some of its southern half extends into the town. The road between Burgas and Varna divides the lake in two halves which have different characteristics. The northern part is a firth, while the southern part exhibits the characteristics of a lagoon. In total, the lake covers more than 7,200 ha, it is nearly 9 km long and 4.3 km wide. The natural coastline habitats have been converted into salt pans in 1906. The area under water has been divided into pools of different size by dykes and embankments. The lake is only 30 cm deep, and it its water is supersaline. Salt is produced in the traditional, environmentally benign manner and has no negative effects on the inhabitants of the reserve. The lake is a good example of a harmless economic activity which even aids and preserves conditions that are conducive to the presence of large biodiversity in the region.
The diverse habitats attract many bird species as grounds for feeding, nesting and rest, transforming the lagoon into a site inhabited by the highest numbers of birds in Bulgaria. More than 315 bird species of all 450 occurring in Bulgaria have been sighted in this lake.
Atanasovsko Lake protects a diversity of habitats. Most typical are the shallow pools divided by dykes and embankments, without vegetation, or covered by common glasswort in varying degrees. This is, also, the most widespread habitat type in the lagoon. Fresh-water bodies exist along the boundaries of the lake, covered by hydrophilic vegetation where club rush, narrow-leaf and broadleaf cattails prevail. The lake is surrounded by small fresh-water pools, swampy meadows, a system of channels and dry lands overgrown by field sedgewort, bulbous bluegrass, perennial ryegrass and other vegetation.
The dykes and the embankments give shelter to nests of black-winged stilts, avocets and Kentish plovers. Little terns keep these birds company. Sand martins also breed in the lagoon or along its banks, although in smaller numbers. It has been chosen as the symbol of the reserve. These species nest in colonies. Frequently, group protection of the colonies is enjoyed by oyster catchers, Mediterranean gulls and gull-billed terns.
The Atanasovsko Lake lagoon lies along Europe's second largest migration route, the Via Pontiica. It is a typical 'narrow migration front' site used by migratory hovering birds. Around 240,000 white storks, more than 30,000 white pelicans and around 60,000 raptors can be seen here during migration in the autumn. This is the place where migrating white pelicans and Dalmatian pelicans, together with marsh harriers and red-footed falcons concentrate in the highest numbers in Europe. The Atanasovsko Lake is second only to the Bosporus in the numbers of lesser spotted eagles flying over during migration.
The shallow supersaline water of the lagoon freezes over only in very cold winter. This makes it the preferred overnighting place for wintering Dalmatian pelicans and white-fronted geese and red-breasted geese. The Atanasovsko Lake is the most important breeding and wintering location for shell-ducks.
Due to this legal protection, and due to the efforts of many scientists and nature conservation work, the Atanasovsko Lake lagoon continues to be:
Scientists from the Bulgarian Academy of Sciences, visiting the lake during the 1970s, have been captivated by the large diversity of birds they have observed. Scientific-research field stations have been established as a result and efforts to protect the lagoon have been initiated by those scientists. The northern half of the lake was designated a reserve in 1980. The second half of the lake and some areas along its banks were designated as its buffer zone during the next year. In 1984, the Atanasovsko Lake was designated a Wetland of International Importance according to the Ramsar Convention, and the Ramsar site was expanded in 2003. In 1989 the territory was declared a key ornithological territory (KOT) by BirdLife International. In 1989 the lake was designated a CORINE site for its European importance for the conservation of rare and endangered bird species. Conformity with the Protected Areas Act required re-designation of this protected area as a 'maintained reserve' in 1999. In 2007, the buffer zone became 'The Burgas Salt Pans Protected Area'. As of 2008, the Atanasovsko Lake is part of the European Natura 2000 network.
• Bulgaria's richest bird site;
• Bulgaria's largest salt production site;
• Bulgaria's largest deposit of curative mud.