The lake Durankulak is the northernmost coastal natural lake in Bulgaria. Located in a old river valley at 0,5 m altitude. Its surface is of 350 ha, and its depth is of maximum 4 m, while the average is of – 1.4 m. Its shores are small, heavily dissected. To the east a wide stripe of sand (150 m), 3 m high, separates it from the Black Sea.
Without draining, the lake is fed by rainfall and karst water. Its waters are brackish, because of the sea water that reaches the lake when large storms or sand trickles through the barrier. The Lake of Durankulak falls falls into the climate region of the Black Sea of Bulgariei.
The winters are comparatively cold and the lake freezes often and the summers are summers are not hot. Rainfall amounts are small – about 480-530 mm. Due to the large north opening here are blowing the northerly strong winds – a speed twice higher compared with winds from the south coast.
TheLake of Durankulak is one of the most important wetlands from Europe. It is included in the Ramsar List and has been recognized as important ornithological area of global concern. Here are nesting, wintering and rest during migration on the migration route Via Pontica an extremely large number of birds, including many rare and endangered.
In the Durankulak Lake are protected 260 species of rare plants and animals and those endangered. Its south shores are covered with steppe vegetation and in the water are growing the algae (more than 92 species), as well as various marsh and aquatic plants (reed, rush, water lily – more than 48 species), and on the sand beach – dune plant. In the lake live 17 species of fish – carp, crucian carp, bream, endemic species of gobies, perch, catfish. Durankulak and Shabla lakes are one of two places in the world for red-breasted goose wintering – a species endangered globaly. It is surprising, when, in early winter mornings, the sky becomes dark by flocks of hundreds of thousands of geese flying searching for food.