Kendra found the pool full of water and nobdy around. She breathed a sigh of relief.
Then she felt it: the water calling to her. It took all her self control not to run and dive straight into the pool. The itch was as bad as it had ever been. Kendra felt her legs weaken but she took a deep breath and focused. The need to transform was almost too much to control.
Kendra headed to a part of the pool out of sight of the doors. She wondered if she should stash her bag and clothes behind the bleachers and dive in, or if she could get away with just removing her shoes and underwear and sit on the edge of the pool with her feel in the water (she wore a skirt)?
And with that thought of the water it became too much to resist. Kendra stumbed and landed on the concrete, fortunately not really hurt. She saw the telltale purple splotches begin to appear on her legs and she quickly pulled off her shoes. Her toes were already losing their definition. She pulled off her underwear just in time. Moving down from her crotch, her legs began to meld together until they were a single tail all the way down to her heels. Her feet flattened out into fins and her knees lost all defintion. The purple color spread from random splotches until everything from her waist down was that color.
Kendra lay on the concrete breathing heavily from the transformation. But changing her mer form wasn't enough. Her tail felt parched and the water still called.
She pulled herself the several feet to the end of the water and dipping in her tail. The chlorine mean it wasn't as good as the ocean or a river or even the bathtub, but the itch finally subsided. Kendra finally felt better. And she made a decision. Stripping off the rest of her clothes - blouse, bra, and skirt - she slid off the edge and into the water until fully submerged.
Ah, this was the life: weightless underwater and free of the land. She turned and kicked with her tail, propelling her toward the far end of the pool.