Salmydessos

The town is now called Kıyıköy in Turkey and is located in the Sea of Marmara

According to one source an ancient city on the Black Sea, erroneously located on the Hellespont in the myth involving King Phineus and the Argonauts. In gratitude for their relieving him of the Harpies, Phineus advised Jason and the Argonautshow sail between the Clashing Rocks. This peril supposedly lay ahead of them, on their route between Salmydessos and the land of the Golden Fleece. But the real Salmydessos was beyond the location of the mythological Clashing Rocks

For now we will go with the erroneous location

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It is referenced in the following articles

Jason and the Argonauts
Thynias