St. Peter Island (Bulgarian: остров св. Петър, ostrov sv. Petar) is a small Bulgarian island in the Black Sea, with an area of 0,025 square kilometres and a height of 9 metres above sea level. Also known as Bird Island, it is located in the Bay of Sozopol, close to the St. Ivan and St. Cyricus Islands. As it was not mentioned in any sources until the mid-19th century, it is presumed to have separated from the larger St. Ivan Island (which is a few hundred meters to the west) as a consequence of some kind of natural phenomenon around that time. Archaeologists have discovered the ruins of a Bulgarian National Revival-time chapel, as well as traces of ancient pottery.