WELCOME TO THE MOST MAGICAL PLACE ON EARTH...
There are very few people in society who are even aware of the existence of the supernatural; the secret has been very carefully guarded. The island is kept hidden by a spell that makes it seem like it doesn't even exist, and those who may spot it by ship or plane are lead to believe that the area is extremely dangerous to travel through. Even those who approach the island regardless are ushered away by seemingly violent weather and waves. To the world, it is the equivalent of the Bermuda Triangle.
Those of age who are discovered to have abilities are brought to the Academy as soon as possible, but sometimes their abilities aren't detected until after some sort of tragedy. Often you'll hear of islanders losing control of their abilities to a destructive degree, being brought to a scientific lab, or whatever else you as a writer can come up with.
The Island was discovered somewhere in the 1400s. The first inhabitants were pirates, seeking a safe haven from the growing naval forces treading the waters.
The Academy itself was established some time in the late 1700s, and has been housing students, teachers, and others that society doesn't want or need since its creation. Headmistress Cordelia Moor, the founder, created Starlight Academy with the desire to bring hope to those like herself and to allow them the education and normalcy that she never had. It is there that students strive to be more than what they could be.
As the Academy slogan says, "Abyssus Abyssum Invocat", in English "Deep Calls to Deep". It is easy to stray, but we must always be on guard to strive for what is good and honorable and rise to be above the turmoil of those who use their gifts to cause strife.
But the island is more than just the school.
Now in modern times, many of the islanders are also supernatural, seeking a peaceful home away from the harsh realities of humanity.
Creatures, experiments, time travelers, immortals and more take haven in the city and countryside, safe from the outside world. To wander the streets and be free is worth the price of living in the bubble of isolation from the world.