SymplegadesThe Clashing Rocks

The deadly rocks (or islands) which stood at the narrow passage between the Propontis (now called the Sea of Marmara) and the Euxine (Black Sea).

The twin rocks were located near the entrance to the Euxine and would clash together whenever any living thing tried to pass between them; when the Argonauts were on their way to Kolkhis (Colchis) to retrieve the Golden Fleece, they were forced to negotiate the formidable Clashing Rocks, which were also called the Kyanean (Cyanean), i.e. Dark-Rocks.

The blind prophet, Phineus, told the Argonauts to send a dove through the rocks before they attempted to sail their ship through; if the dove survived, it would be safe for their ship, the Argo, to proceed; the dove made it through the Clashing Rocks with only the loss of its tail feathers and the Argo sailed boldly into the passage; Athene held back one of the rocks with one hand and pushed the Argo through with the other; after the Argo survived the Clashing Rocks they became stationary islands and never menaced sailors again.

• Argonautika, book 2, lines 341-359 and 593-610