This ab-solutely RIPS.
Functioning on the job of film to cultivate mood, this is pure adrenaline. Not only from the ticking timebomb of the drill station deep in the Mariana Trench, but also from beasts hiding in the darkness of it. An alien scenario in what amounts to an alien environment here on Earth.
But this never mucks up its otherworldly setting with bogged dialogue or characterization. This builds more on subtextual lore than character, the actors weighted with the responsibility to have their charisma hold the tension under a thin veil of backstory. Do they succeed? Look at the cast and answer for yourself. It characterizes them as the material does. Because at 35,000 feet deep, this posits that maybe the only thing that matters is living.
And the explosions, running, and terrors of the deep would cancel each other out if any looked bad, but this all looks so good. Any questions asked about the lean storyline can be answered in image. Stewart sliding around on the flooded floors, the navigation through the ceiling nest while lights pulse red, Stewart shooting a flare gun into the air and seeing the odds against her survival in height and width. Even the pan shot at the beginning becomes a standout, simply due to the pace-anachronism it becomes.
Sometimes, the job of a genre film as such is to look good and keep the pace. This is a polished bullet train.
The above was taken from my Letterboxd review.