Mind blowing ending! Perfectly sums up the varied aspects and uncertainty of adolescent group dynamics, hysteria, and even altered-state spiritual realities. I loved the progression from the physical (the water), to group pressure/hysteria, to the spiritual realm. Afterwards, I realized that this progression was not only focused on the surface level (exploring various altered aspects), but it was also an allegory of the progression of a girl changing as she enters young adulthood.
By the end, it reminded me of classics such as 2001 A Space Odyssey (foreign compelling societal/world influence), Alfred Hitchcock's horror movies - and even the Catcher in the Rye. This movie was profoundly spiritual (hopefully not of an evil origin but it left that open) - in fact, the end left the door open for you to decide the origin of the "Fits" and it's significance in the young heroine's life. (Spirits, Hysteria, peer-pressure, etc . . .) Although, yea, she did kind of levitate so . .(unless she just imagined that).
On the most basic level, I guess she just fully opened up and allowed herself to become one of the dancers. She let go and let it enter her. She allows the dancers to enter every aspect of her old-style self that was holding her back from this, such as the boxing ring, the training steps, and other scenes. She opened herself to full initiation: she was "all-in" for better or worse.
Great Movie! Multi-dimensional!