A haunted house that is UNDERWATER! Conceptually it is quite cool and even starts enthusiastically, but it doesn’t sustain. It drowns the drama when it most needs to breath.
A fresh concept, with the framing device of an explorer Youtuber couple and their cams telling the story, with the natural confining drama of scuba diving and ticking oxygen clocks, is a highly effective blueprint. What doesn’t work as well is the actual scares. The chase wasn’t as engaging nor were the poltergeisty shenanigans.
The ending did provide some buoyancy to my overall opinion - bleak and grasping, just the way I like it. The film though doesn’t evolve or execute past its conceptual backbone.