Tragic story of couple who vanished after being left behind on diving trip and were never seen again

If you’re wondering about whether to go for a swim in some open water, this horrible true story might put you off.

After being stranded on a diving trip in Australia, Eileen and Tom Lonergan - from Baton Rouge, Louisiana - were never seen again.

The couple's tragic story was even adapted into the notoriously tense film, Open Water:

It was on 25 January, 1998 when the pair signed up for a day trip to explore the Great Barrier Reef after stopping in Australia on their way home from a holiday in Fiji and Tuvalu.

Eileen, 28, was said to be an experienced scuba diver and had managed to convince her 34-year-old husband to take up the hobby with a trip to the famous coral reef - something on many diver's bucket lists.

The couple and 24 other passengers then boarded a boat called Outer Edge, manned by skipper Geoffrey 'Jack' Nairn, and travelled 60km off the coast.

After diving for the day, a headcount was conducted and the boat returned to the mainland.

However, something went wrong during this head count as it turned out that the couple were not on board the Outer Edge when it headed back to dock.

QLD Police

Tragically, it was only two days later that a bag belonging to the married couple was discovered on the vessel.

This little detail led to the suggestion that Eileen and Tom must have resurfaced from the last of the three dives to find the boat had left without them, leaving them stranded in the ocean.

As soon as this was realised by authorities, a wide-spread air and sea search took place but tragically, the couple were never found.

A month after their disappearance in February, 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.

Soon after, dive jackets, tanks and one of Eileen's fins turned up.

According to reports, nothing suggested their lives had come to a violent end - even though in the film Open Water, the couple are depicted as victims of a shark attack, something that isn't proven to be true.

But something that did happen came months later, when a fisherman found a dive slate 160km away which had a note engraved on.

QLD Police

The note 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!!!"

This tragically shows that the couple were alive for at least one day after being stranded.

In the end, the Outer Edge skipper was charged with manslaughter.

He tried to explain 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 counting.

He was later found not guilty by a jury, however, his company pleaded guilty to negligence and went out of business.