This felt like a standard low-budget monster movie that couldn't overcome its limitations in terms of financing, writing, and directing. The story involves divers and scientists exploring an uncharted underwater cave system in Romania—though the reason for their expedition has escaped me—and discovering previously unknown creatures living there. While the basic storyline is familiar, it didn’t necessarily mean it couldn't bring something new to the table. At least, that’s how it seemed initially. The movie progresses slowly, with characters frequently stating what they are observing aloud, which felt like listening to an audio recording. A significant portion of the film relies on exposition rather than visual storytelling, a misstep for this type of production. The actors seem committed to their roles and appear to be giving maximum effort given the circumstances. However, the script is flawed; there’s very little development of the characters, and they often act in ways that don't make sense. I realize it’s an action/horror film, and rational behavior isn’t always expected, but the reactions of experienced divers when things go wrong felt foolish and unbelievable. Some of the creature designs are intriguing and visually appealing, with surprisingly decent computer-generated imagery for a movie of this scale—and that's what prevents it from being entirely worthless, raising it to merely mediocre status. Sadly, the action sequences are edited so quickly that it’s often difficult to follow what's happening. It could have been worse, but it likely should have been better; perhaps a more experienced director might have improved things. Ultimately, the biggest problem is the script's shortcomings, which may have sealed its fate from the start. Perhaps giving it a rating of 5 out of 10 is being too kind, but a score of 4 seems overly critical, so that’s my assessment.

Source on TMDB