The symplegades ( Greek Συμπληγάδες “colliding”) in Greek mythology are rocks  , floating at the entrance to Pontus Euxinus : colliding, these rocks destroyed ships.
Symplegades, figuratively, mean simultaneous two-sided danger.
According to the myth of the Argonauts, the wandering rocks of the Simplegade are located near the Bosphorus, at the entrance to Pontus Euxinus ( Black Sea ). When the Argonaut ship approached them, Euphemus released a dove (according to another version - a heron  ), which flew through them  . When the ship " Argo " was able to sail between the rocks, they stopped forever  .
Wandering or colliding rocks, “pushing mountains” are present in many myths of the peoples of the world  .
The source for the myth was the Kyaney Islands ( Greek Κυάνεαι νη̃σοι ) - two small rocky islands that, when leaving the Thracian Bosphorus to Pontus, were dangerous for navigation and, according to legend, the Argonauts were floating and collapsed   .
- Pseudo-Apollodorus . Mythological library I 9, 22; E VII 20-21
- Pliny the Elder. Natural History VI 32 // Comment by D. O. Torshilov in the book. Gigin. Myths St. Petersburg, 2000. P. 41
- Apollonius of Rhodes. Argonautics II 549-566
- Obnorsky N.P. Simplegades // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- Kianee Islands // The Real Dictionary of Classical Antiquities / ed. F. Lubker ; Edited by members of the Society of Classical Philology and Pedagogy F. Gelbke , L. Georgievsky , F. Zelinsky , V. Kansky , M. Kutorgi and P. Nikitin . - SPb. , 1885.