The water rises floor by floor. That’s the whole engine of The Great Flood (대홍수), and for a while it’s enough — an AI researcher and a small child stuck in a high-rise as the sea climbs the stairwell behind them, doing the grim arithmetic of how many floors are left before the roof. Then the film does something stranger. Director Kim Byung-woo, the man behind the single-location pressure cooker The Terror Live, isn’t really making a survival movie at all. Somewhere past the midpoint the flood stops being the point, and questions about artificial consciousness, repeated timelines, and what’s actually real start seeping in like the water itself.
The premise
A catastrophic global flood is swallowing the world. Gu An-na (Kim Da-mi), an AI researcher, finds herself trapped in a flooding apartment complex alongside a young girl named Ja-in, and the two of them set out to reach the roof, where rescue might be waiting. On paper that’s a confined disaster thriller, and the early stretch plays it straight: limited space, rising threat, a clock you can practically feel.
But the genre label here is science fiction for a reason. As the climb continues, the film leans into its bigger preoccupations — artificial consciousness, motherhood, what survival even means when the ground beneath the story keeps shifting. I’ll leave the turns alone; part of the pleasure is not knowing which kind of movie you’re in until it tells you.
Where to watch
This is a Netflix original film, streaming worldwide on Netflix with no separate theatrical or home-video distributor. It had its world premiere at the 30th Busan International Film Festival on September 18, 2025, in the Korean Cinema Today – Special Premiere slot, then landed globally on Netflix on December 19, 2025. If you’re hunting for a Blu-ray or a rental window, there isn’t one — Netflix is the whole release.
One small housekeeping note for the completists: runtime is listed as 106 minutes by some sources and 108 by others, a minor discrepancy between the Korean and English Wikipedia entries. Either way you’re looking at a tight feature, not a sprawling one.
The cast
Kim Da-mi carries the film as Gu An-na, the AI researcher whose technical mind becomes the closest thing to a lifeline as the water keeps coming. After her breakout in The Witch: Part 1 and the runaway success of Itaewon Class, she’s an interesting fit for a role that asks for cold competence and something more fragile underneath. Opposite her is Park Hae-soo — the Squid Game ensemble’s Cho Sang-woo, and a fixture of Prison Playbook — as Son Hee-jo, a security operative pulled into the chaos. Kwon Eun-seong plays the child, Ja-in, the small constant who keeps the survival stakes human rather than abstract. There’s also a supporting turn whose performer’s name varies across sources (you’ll see Jeon Hye-jin or Jeon Yu-na depending on where you look), so I’ll flag that spelling rather than pin it down falsely.
How it was made
Here’s the part I find genuinely impressive. There are no postcard filming locations to send you to — no Seoul landmark you can go stand in front of — because almost none of this was shot in the real world. The production built a water tank with a partial apartment set ringed by chroma-key green walls, then used dry-for-wet and underwater photography inside special-effects studios. Principal photography ran roughly from July 2022 into January 2023 in South Korea, but no specific public site is documented; the flood you’re watching is engineering, not geography. Kim Byung-woo co-wrote the screenplay with Han Ji-su, and the whole thing reads as a deliberate technical gamble — a contained, manufactured deluge built to feel inescapable.
Worth your time?
If you came up loving single-location thrillers — the ones where the threat is right there and there’s nowhere to go — the first act of The Great Flood is squarely your kind of tension. Whether you stay onboard depends on how you feel about a disaster movie that quietly mutates into a question mark about AI and reality. Some viewers will love the swerve; others will want the water to just stay water. For anyone who enjoyed Kim Byung-woo’s earlier work, or who likes their Korean genre films willing to risk something stranger than the marketing suggests, it earns the 106-odd minutes. Go in knowing the flood is only the surface.
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