Durankulak, Bulgaria; September 5, 2020; Durankulak lake is a nature and archeological reserve on the Northern Bulgarian Black sea coast. The lake is an archaeologically very important area. Pit-houses of the oldest known inhabitants of Dobruja, dating to 5100–4700 BC, have been unearthed near the west shore, as well as 3500–3400 BC mound burials and a Sarmatian necropolis from Late Antiquity. The Big Island of Lake Durankulak is particularly important, as it is the site of a Neolithic settlement of 4600–4200 BC, a cultural monument of national importance.