The Datça, Cnidus/Cnidos, or Reşadiye peninsula is an 80 km-long, narrow peninsula in Muğla province, southwestern Turkey, separating the Gulf of Gökova (to the north) from the Gulf of Hisarönü.
The name Reşadiye honored the Ottoman Sultan Mehmed V Reşad.
The modern city of Datça is located at its half-way point, and the ruins of ancient Cnidos at its tip.