St. Ivan Island, also known as St. John Island, is the largest island in the Black Sea on the waters of Bulgaria, with an area of about 0.66 km². It is located 1 km from Sozopol, and can be reached by boat from Sozopol Bay. The island is a protected It was considered a sacred place for the ancient Thracians who settled there in the seventh century BC. It also contains some antiquities dating back to the early Middle Ages, and it is subject to continuous archaeological research. In addition, this island is home to many species of birds, as more than 70 species have been recorded on and near it, and it is also inhabited by the largest colony of European gulls.