Seriphos was the island where Perseus and Danae were cast ashore in a chest.
Acrisius, king of Argos, feared a prophecy that his daughter’s son would kill him. To prevent that future, he placed Danae and her infant son Perseus in a chest and set it adrift. The chest survived the journey and reached Seriphos, an island in the Aegean Cyclades.
The fisherman Dictys discovered them and provided protection. This rescue allowed Perseus to grow up before becoming involved in the conflict with Dictys’s brother, King Polydectes. The island therefore serves as the setting for both Perseus’s childhood rescue and his later return with Medusa’s head.
The location is not Argos, where Perseus was born, and not Crete, another important island in Greek mythology. Seriphos is specifically associated with the chest, Dictys, and Polydectes.