While it's not a real island, the film was actually shot on the Greek islands of Skopelos and Damouchari.
* Skopelos was used for most of the filming, including the iconic scenes at the church and the charming village square.
* Damouchari was used for the beach scenes, specifically the famous "Dancing Queen" sequence.
So while the fictional island of Kalokairi is a creation for the film, the stunning landscapes of Skopelos and Damouchari brought it to life.