Natalia Keogan of Paste rated the film 8 out of 10, asserting, "There's a very good chance that the film's zero-sum game will not appeal to everyone, least of all those who flip it on with the hopes of a tumultuous sex-fueled affair. More akin to the similarly Affleck-starring Gone Girl than Fifty Shades of Grey—or if we're using Lyne's filmography as a reference, more akin to Lolita than An Indecent Proposal—Deep Water is a sweat-inducing psychological scheme that is constantly aiming to intrigue and titillate. The paperback pulp origins of Highsmith's original story are kept intact, alleviating any semblance of eye-roll worthy ridiculousness that doesn't at least try to make an interesting point. As each shocking revelation tacks on another clue in the sprawling mystery, the audience isn't sure just who or what to believe—making the film's fiery ending all the more jaw-dropping." Rex Reed of Observer Media gave Deep Water a grade of 3 out of 4 stars, writing, "Ben Affleck plays a diabolical husband with the calm, resolute demeanor of a mathematician solving an elaborate calculus problem. Ana de Armas plays a wife with carnal ingenuity. She keeps finding handsome new guys to reduce the boredom, and he keeps thinking up ingenious new ways to murder them. Heading the exceptional supporting cast is actor-playwright Tracy Letts, as the suspicious neighbor whose radical discovery of the truth fatally backfires. How she finally traps her husband and ends the charade gives the film its “gotcha” moment, but Deep Water has shock effects when and where you least expect them. It's the kind of riveting and dynamic thriller from start to finish we used to take for granted in the good old days, don't see much anymore, and could definitely use a lot more of."
