The city of Sinope is located on the northern most point of Anatolia along the coast of the Black Sea. It was established by colonists of Miletus in the 8th century B.C. In turn, Sinope established its own colonies along the shore of the Black Sea.
It was the birthplace of Diogenes (d. 323 B.C.) and for a while it was the capital of the Pontic Kingdom.
One of the recipients of 1 Peter? Dr. Mark Wilson comments "Sinope was a certain stop in Pontus for the messenger carrying Peter's first letter." (p. 342).
Mark Wilson provides a good summary of the history of Sinope in his Biblical Turkey — A Guide to the Jewish and Christian Sites of Asia Minor. Istanbul: Yayinlari, 2010, pp. 341–345.
At Sinope there is a marvelous museum that houses finds from the area.