It's a scene of watery suspense that could rival any in Steven Spielberg's classic sea monster movie Jaws. And this video starts off like a scene from that film with a spring breaker in a bikini screaming "WHERE IS IT?"
She then proceeds to get more and more hysterical, spouting lines like "I SEE IT! I SEE IT! IT'S RIGHT NEXT TO ME!" just to hype up the tension and terror as you wonder what kind of hideous sea beast it could be. You then see the outline of a manatee lurking beneath the surface.
She obviously isn't aware that these creatures are entirely peaceful and like to graze on seagrass—not the flesh of humans. Still, it makes for entertaining viewing. If you wondered what her friends were doing while this was going on, here's a video from their perspective.