The Greek Monster
Scylla is viewed in many different ways...
In The Odyssey, Scylla is described as a woman.
In Theoi, the picture views Scylla as a man.
In Reddit, Scylla is viewed as a creature, no gender at all.
Many ships would pass through Italy and Sicily, but none returned. This is because ships have to enter between Charybdis and Scylla, either you enter closer to Charybdis or Scylla but no matter what, the ships aren't going to make it back.