On 25 January, 1998, a married couple from America went on a group diving trip in Australia.
25 years later, the couple have still not been found but a heartbreaking message from the pair was discovered.
In time, Tom and Eileen Lonergan's story inspired a movie titled Open Water.
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The couple had travelled to the Coral Sea in Australia to take part in the diving trip as they made their way home from a holiday in Fiji and Tuvalu, 10 years after they tied the knot.
Eileen, 28, was an experienced scuba diver, and after convincing her 34-year-old husband to take up the hobby, a trip to the famous coral reef seemed an ideal place to visit.
Alongside 24 other passengers, the couple boarded a boat called Outer Edge, manned by skipper Geoffrey 'Jack' Nairn.
They travelled 60km off the coast to where the underwater adventure began, and once the diving was done for the day, a headcount was conducted and the boat returned to the mainland.
It wasn't until later, however, that it became clear the headcount wasn't as accurate as initially thought.
It transpired the couple were not on board the Outer Edge when it headed back, indicating Eileen and Tom must have resurfaced from the last of the three dives to find the boat had left without them.
In the days that followed, a wide-spread air and sea search took place to find the divers who had been left behind.
Weeks passed and there was no sign of the couple, until one month after their disappearance, a wetsuit in Eileen's size washed up on the northern Queensland shore with tears to it that experts said would have been a result of contact with coral.
After that, dive jackets, tanks and one of Eileen's fins turned up as well.
Unlike Open Water, in which the couple are depicted as victims of a shark attack, there was nothing to suggest Tom and Eileen's lives had come to a violent end.
Months later, a fisherman found a dive slate 160km away which read: "[Mo]nday Jan 26; 1998 08am.
"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!!!"
The date on the slate indicated that the couple were alive for at least a day.
Following the incident, the Outer Edge skipper was charged with manslaughter.
He explained how he had ordered a crew member to carry out the count, and the numbers had become confused because two passengers had jumped into the water halfway through.
He was later found not guilty by a jury. His company pleaded guilty to negligence and went out of business.
Topics: Australia, TV and Film, World News
Claire Reid