Theory 1: The visitors are stuck in a time loop at the beach.
Fair warning: we've got some spoilers ahead for Netflix's In the Tall Grass! One possible scenario is that the mysterious beach traps the visitors in some sort of time loop where they're forced to relive their mortal lives over and over again. As Twitter user @iank366 pointed out, the film does share a similar vibe with the onscreen adaptation of Stephen King and Joe Hill's In the Tall Grass. In the Netflix horror film, we see the characters get trapped in a maze and die over and over again in a twisted time loop, their decomposed bodies fertilizing the ominous grass field.