"Open water", directed by Chris Kentis (2003)

Based on an actual event, Open Water tells the story of a young couple, Daniel and Susan, (Daniel Travis and Blanchard Ryan), who go to the Bahamas to scuba dive the coral reef, and are accidentally left behind in the ocean. The couple boards a tour boat that is crowded with divers; after the first dive of the day, the captain makes a mistake on the numbers of divers who have surfaced from the dive and are aboard. When the number reaches 20, the boat leaves the area and goes to the next site. Daniel and Susan did not stay with the group underwater, but they were supposed to be back within 35 minutes. They were 5 minutes late and the boat left without them. Susan blames Daniel for being left behind, and their ordeal goes down the drain from there. After several hours, sharks begin to circle them. They begin to realize that their workaholic life is not important anymore. Only if they had a second chance, they would change. Douglas Young (the-movie-guy)

My opinion: That's a terrifying movie... based on true event... makes it even more freaky!