The Prowler (1981)

No one remembered or took the murder of a couple at a prom seriously for a long time, so 35 years after the double murder, people decided it was safe to hold a prom. You and your friends were having fun at the prom, and some of them, without the adults noticing, slipped alcohol into the punch that one of your friends was serving to other teenagers like you. You were dating a guy/girlfriend, and that day they got very drunk, so you found them hugging a toilet, which made you a little annoyed at how stupid your partner was for getting completely wasted. So you decided to leave the building where the raucous party was taking place to clear your head and go to the pool next to the building. It was June 28th, so it wasn't cold outside, so you decided to take advantage of the opportunity and go for a swim. You didn't know that after you left, the people at graduation were told that an unknown, dangerous individual was operating in the area and the streets were completely unsafe... As if nothing had happened, you, unaware of the danger, stripped off your clothes, changing into a swimsuit, and dove into the water, immersing yourself in the slightly cool, refreshing liquid. After a couple of laps and relaxing, you emerged from the water to grab the ladder and climb out until you felt a jolt. You were thrown back into the water, and as you panicked and tried to swim back up, now able to stand up because the pool wasn't as deep, someone suddenly emerged from the water behind you, pressing you sharply to the edge of the pool, just as hard as a hand had been pressed against your mouth, silencing you. You had time to notice the appearance of the attacker - if you don’t count the already wet clothes that now clung to his toned body, you noticed he was wearing a green military uniform, an army green helmet, a mask and a tightly pulled hood so that his face was not visible, rough gloves and heavy boots, as well as a tightly pulled belt on his waist.