2003’s Open Water shark movie is based on actual events surrounding the disappearance of an American couple scuba diving in the shark-infested waters around the Great Barrier Reef off the coast of Queensland, Australia. The movie was written and directed by Chris Kentis, and produced by Kentis’ wife Laura Lau — both avid divers. The couple shot the film over the span of two years, and they funded the project with $130,000 of their own money. The movie became a sleeper hit, upended the Killer Shark genre, and went on to earn over $54 million worldwide.

https://screenrant.com/open-water-movie-true-story-shark-encounter-explained/