Old (2021) written and directed by M. Night Shyamalan
Several small families visit a tropical island resort where the staff cater to their every need. Select visitors are invited to a secluded beach on "the other side of the nature preserve" where they can spend a magical day of surf, sun, and happy memories that will last their lifetime. A bickering couple on the verge of separation takes their son and daughter. Another couple brings his mom and their daughter. The third couple don't have children, probably because the wife has seizures. They all look forward to a relaxing day at the resort's exclusive little treasure.
A fourth couple had an early ride to the beach and the guy has been sitting in the shade, waiting for his woman to come back from a swim out into the ocean. Her body drifts back to an inlet where the kids are playing. The kids freak out and the adults have a hard time dealing with the dead body. The beach has no cell coverage and anyone who walks back to the road through the slot canyon path quickly blacks out and is back on the beach. There seems to be no escape. And the three kids are rapidly growing older. One of the kids sees some lights on a faraway ridge but they can't tell if the flashes are just reflections or people watching them. Things get tough from there.
The movie does a good job establishing the characters as people with real-world problem. They've come to the resort to get a break but the stress of the beach forces several of them to the breaking point. They have to deal with the mystery of what's going on as well as their own insecurities and conflicts. Viewers have a hard time figuring out what's going on until the end. The explanation of what is happening and why is less satisfying in this film than in other Shyamalan movies. The purpose is morally dubious (which the film acknowledges) and not entirely credible. Even so, I found the movie diverting. I've watched it once, enjoyed it, and probably won't watch it again.