Atanassovsko Ezero Reserve. It covers 1050 ha of Lake Atanassovsko, which is the northernmost of the three Bourgas lakes. It is in the vicinity of Bourgas and is one of the lagoon lakes - a shallow bay, which is separated from the sea by a narrow sand outcrop. It is never icebound in winter owing to the high salinity of the water. Atanassovsko Ezero is the largest stopover in Europe for the migrant birds that use the Via Pontica. During the migratory season over 500,000 birds of 33 species make a stop there. The place is on the Convention on Wetlands of International Importance Especially as Waterfowl Habitat (The Ramsar Convention).