Here is my plausible made-up story, my guess:
She is playing around with a hotel employee. She breaks a minor rule (e.g. wondering into a employees-only area) and runs from the employee in a teasing way when caught. She does this for three reasons:
- Youthful goofiness while on vacation
- Flirting, inviting the employee to “chase” her
- A manic episode giving her an urge to run around and engage in risky attention-seeking behavior
She ducks into the elevator. She presses all the buttons, which is a trick she knows to hold the elevator for a minute. Her plan is for the employee to run past the door, not thinking to look for her hiding there. Then she would run back the opposite way, making her pursuer turn around and run back the way they had come. She is disappointed when he never runs by. He probably had better things to do, but she hopes he’s playing her cat-and-mouse game and is hiding. She gesticulates and calls out, taunting him to come out and apprehend her. She flamboyantly counts on her fingers 10 seconds before she’s going to get away. Nothing happens. He’s moved on. She gives up and looks for another source of attention. She even considers stealing something trifling or telling some bizarre lie.
She manages to get someone chasing her again. This time she gets to the roof, using some trick she learned from the same person who told her the elevator hold trick. This time employees keep chasing her. She imagines they’re angry. The danger, attention, and thought that she’s crossed a line excite her. Maybe subconsciously she hopes an avuncular security guard will catch her and see this as a cry for help, and he’ll shower her with kindly attention. Or maybe it will be young man who will be easily sweet-talked into breaking the rules just for her. Or it could be an angry young man who will take advantage of her. Or maybe it’s a police officer, and she’ll be jailed, and it will be like an international mini-incident. She’s scared, but she loves attention and the fact she doesn’t know what will happen. She climbs the water tower ladder, intending to hide up there and double back, just as in the elevator. But it’s hard to hide there. She sees the hatch. It's hard, but not impossible to open. She doesn’t know it’s a water tank. She imagines it’s some kind of service crawlway, storage, or something like that. She jumps in, without even knowing it’s a deep container of water with no way out. It’s half a game, and half an imagined action movie. Once she’s in the water she can’t get out of the tank. She takes off her clothes to facilitate swimming. She eventually drowns.
The guards who chased her give up the cat-and-mouse game quickly. They think nothing of it until she goes missing. They don’t want to be blamed. When she turns up dead, they feel awful. They probably should have followed up. People think of 21-y/o’s now the way people used to think of 17 y/o’s back in the 90s when I was 17. It’s unfortunately more so for females because sexism has not improved any. At best people will say they should have done more to looks after this poor lost “child”. At worst, they’ll suspect they murdered her. They and their colleagues know they’re innocent. They cover up the fact that he was chased her around the time she went missing. The police conclude it was an accident, too, and resist releasing anything that would make the tragedy any more of a public spectacle than it already is.
If I’m right in even half my guesses, I would consider that good. It’s all guessing.