All fairies are natural hydrokinetic beings who can shape and control water if taught properly by someone more experienced.
Tourmaline, the orange guardian, teaches it. Sunburst, his apprentice, appears to be quite skilled at it. When Elina performed it, hers was magnificent. Although her magic aimed at Sunburst and nearly made her lose her powers, it was still described as "very impressive", but lacked control.
Water Magic is the first skill used to create the chamber where the Flight of Spring takes place.