Regardless of my review/comments of the film, saying it was without real meaning, I will go forth with a very simplistic revelation about the meaning/message of the film.
Please throw away your lurid views about pedophilia, and a dark, manipulative environment.
This film (by a woman I might add) is a symbolic view of childhood as seen through a child's eyes...albeit, a now adult woman director who used a 100 year old unfinished story as a motif.
Why the mystery, and things that don't make sense?
Why the forbidding and manipulation as some may call it?
Think back to your own childhood (especially if you are female) This is a child's view of a grownup world; regimented, told what to do, even though it makes no sense to you.
Think of all your childhood fears, nightmares etc. This is how a child responds to the world. I can feel akin to these girls because though I am male, I too grew up in boarding schools. The "school" IS a metaphor of childhood; insular, and self-contained...segragated from the world of adults except the few that are caregivers and teachers.
And the ending, the fountain....yes, I think symbolically it was a stunning ending, and least least to me, unpredictable at first, but naturally putting everything into perspective. The girls first seeing the "outside world" is a natural step from puberty into adulthood. Yes, the fountain, the boy, the coy smile of Bianca, is indicative of sexual awakening, which is exactly the point of this movie...the gradual loss of innocence/childhood.
The film also uses water as a metaphor. Two examples would be birth itself, which the child from a sack of fluid is born, and death (the only way a child can excape childhood is by growing up, or untimely death) water being the ether or substance that all life comes from and where one returns too. That is why the fountain morphs back in to the watery beginning of the film. Bianca and the other girls have reached puberty, sexual awakening, and therefore are no longer "children" nor innocent.
Was it a great film? Not really, but I do commend the director for her first try, and I also condemn the many viewers who can only see darkness, evil, and pedophilia everywhere...which ironically, is what the film is implying as well.
Anyone who screams pedophilia had better read James Kincaid's epic work: Child-Loving: The Erotic Child and Victorian culture.