A titular see, suffragan of Amasea in the Hellespont. There was a town of this name near the mouth of the Thermodon, the modern Therme-Tchai, mentioned by Herodotus (IV, 86) and by most classical authors. Scylax calls it a Greek town while Diodorus (II, 44) makes it an Amazonian foundation. Mythology made this region the native land of these warrior-women.
After Mithridates withdrew his troops from Cyzicus, Themiscyra was besieged by Lucullus and was courageously defended by the inhabitants. The town must have been destroyed on this occasion, for neither Mela nor Strabo mentions it, while the latter treats extensively the country of Themiscyra, which he makes the subject of great eulogy. It is, however, mentioned by Ptolemy (V, vi, 3). It is not found in the "Notitiae episcopatuum" nor in the "Oriens christianus" of Le Quien. It was situated near the present Therme on the Black Sea, in the sanjak of Samsoun and the vilayet of Trebizond. The country is one of the richest and most beautiful in the world.