She appears to be a exigent teacher. She's a talented diver.
A water sprite (also called a water fairy or water faery) is a general term for an elemental spirit associated with water, according to alchemist Paracelsus. Water sprites are said to be able to breathe water or air and sometimes can fly. They are mostly harmless unless threatened.
These creatures exist in mythology of various groups. Ancient Greeks knew water nymphs in several types such as naiads (or nyads), which were divine entities that tended to be fixed in one place and so differed from gods or physical creatures. Slavic mythology knows them as vilas. Water sprites differ from corporeal beings, such as selkies and mermaids, as they are not purely physical and are more akin to local deities than animals.
At the dive class when Duchess was in the spellementary school, the students was lined up along the edge of the swimming pool. "Today we will learn to do a swan dive", the teacher, Mrs. Watersprite said, pointing to the highest board. The students lined up at the bottom of the ladder. There were many trembling legs and terrified squeals as they climbed. "this is the most graceful dive of all.", she explained. "Put your hands above your head, lean forward, and jump! Then spread your arms wide, like wings."
One by one the students jumped. Some clawed at the air as if trying to stop the fall. Some landed on their bellies. Others went feet first. "No, no, no!" Mrs. Watersprite hollered. "That was not graceful".
Duchess went last. She raised her arms above her head and gripped the of the board with her toes. It was a long way down.the other students looked small, some shivering beneath their towels. With their faces turned upward, they waited to the "ugly duck girl" to jump.
"Dive" Mrs. Watersprite ordered.
Duchess bounced three times, then jumped. Just a gravity grabbed hold of her, she reached out her arms, closed her eyes, and transformed into a swan. The dive was perfection.
When she rose to the surface, the village kids cheered.
And that day the ugly duck girl became the swan princess.