95 min | PG-13 | January 10, 2020 | 20th Century Fox
A drilling crew at the bottom of the Mariana Trench feels the floor crack open. The water comes in, and so does something living in the dark. The premise is a haunted house with eleven kilometers of ocean for a ceiling.
Norah Price is a mechanical engineer working a deep-sea drilling station at the bottom of the Mariana Trench. An earthquake collapses the facility and floods the corridors in the first three minutes. The survivors must walk across the ocean floor in pressurized suits to reach an escape pod, and something down there is hunting them. William Eubank treats this as a survival exercise stripped to the studs. The film is about competent people executing a plan while the dark works against them.
Kristen Stewart plays Norah with a shaved head and a clipped, interior focus that anchors every scene. She narrates in a flat near-whisper that frames the whole film as a confession. Vincent Cassel plays Captain Lucien as a weathered authority carrying a private grief that explains his calm. Mamoudou Athie plays Rodrigo Nagenda with a nervous decency that makes him easy to root for. T.J. Miller plays Paul Abel as comic relief who undercuts the tension every time the film tries to build it, and the character never earns the airtime he gets.
Eubank and writers Brian Duffield and Adam Cozad keep the geography deliberately illegible. The cinematography drowns the action in silt and emergency lighting, so the creatures register as shapes and impacts rather than bodies. That choice hides a thin monster design behind murk, and it also robs the set pieces of clarity when clarity is what a chase needs. The sound design does the heavy lifting instead. Hull groans, suit radios, and the crush of pressure on metal supply most of the dread the visuals withhold.
The film owes an obvious debt to Alien and never pretends otherwise. It moves fast and wastes no time on backstory, which is both its discipline and its limit. The characters exist to be picked off in sequence, and the script gives them just enough personality to mark the order. Stewart commits to a part that asks for more than the material returns. Underwater is a tight, grim machine that works on the level of pure mechanism and forgets to make you care who survives it.