The Sirens were nymphs of the sea. Their beautiful(but deadly) singing would hypnotize sailors who would crash their ships onto the rocks just to get close to them. Ulysses (the same person as Odysseus) successfuly sailed pass the sirens when he and his crew stuffed wax in their ears. Ulysses himself had his sailors tie him to a post on the ship so he would not sail it into the rocks.