“Open Water” is loosely based on the true story of Tom and Eileen Lonergan. In 1998, the Lonergans went out on a scuba diving trip on the Great Barrier Reef in Australia. During the trip, a headcount went wrong and the Lonergans were accidentally left behind. The crew of the boat did not notice their absence until two days later, when they found some of their belongings, but no bodies were ever recovered and both are presumed dead.
Now, a popular belief is that the Lonergans were killed by sharks, but their vest and tanks, which would have helped them stay afloat were later found — and there were no clear tooth marks that would indicate a shark attack. So as much as “Open Water” sells itself as a true story, it likely starts and ends with the initial “left alone at sea” part and not with the savage animal attacks (like these other creature features).
As a result of their disappearance, the government of Queensland introduced stricter regulations for scuba diving trips, like requiring independent confirmations of headcounts from captains and dive masters.
