Open Water is a 2003 film inspired by a true story about an American couple, Tom and Eileen Lonergan, who in 1998 went out with a scuba diving group, Outer Edge Dive Company, into the South Pacific. They were accidentally left behind due to a faulty head count taken by the dive boat crew. There were twenty-six other divers and five crew members, all of whom failed to notice that the couple were not on board.

The film was financed by director Chris Kentis and his wife, producer Laura Lau, both avid scuba divers. The movie originally cost $130,000 to make and was later bought by Lions Gate Films for $2.5 million after its screening at the Sundance Film Festival. (Thanks Wikipedia)