Though not based off a true story in its entirety, Open Water is loosely based on the couple named Tom and Eileen Lonergan.
In 1998, the couple was scuba diving with a group at St. Crispin’s reef in Australia’s Great Barrier Reef. The boat which had transported the group managed to leave the couple behind, none of the guests or crew noticing their disappearance. The couple was left stranded in the water.
It wasn’t until two days later on January 27 that a flag was raised when a bag containing their belongings was found on board the dive boat which had transported them. In the following days, many rescue attempts were started on sea and in the air but the couple was nowhere to be found. Several days later some of their diving gear were found washed up on a beach a few miles from where they were left stranded. As their bodies were never located, it is suspected that the couple may have lost consciousness and drowned.
Fishermen later found a diver’s slate (a device used for communicating underwater) and wrote down what it reportedly read: “[Mo]nday Jan 26; 1998 08 am. To anyone [who] can help us: We have been abandoned on A[gin]court Reef by MV Outer Edge 25 Jan 98 3pm. Please help us [come] to rescue us before we die. Help!!!”