“Aquaslash” (** out of four) was a pointless horror thriller about a group of high-school partiers (Brittany Drisdelle, Paul Zinno, Samatha Hodhod, and others) who have their graduation bash at a water amusement park but someone has murder on their agenda and sets out to systematically kill them off using the rides as a weapon. Professionally directed and acted but takes too long to get going and then wraps up pretty quickly. One scene involving blades on one of the water rides provides the only real thrills in the movie.