A dive boat left two divers behind on the Great Barrier Reef. They were never seen again

Two divers came up from the deep and found an empty sea.

It was 25 January 1998 on the Great Barrier Reef. Tom Lonergan, 33, and his wife Eileen, 28, from Baton Rouge in Louisiana, had been underwater for the third dive of the day. When they surfaced, their dive boat, the Outer Edge, was gone. It had sailed home to Port Douglas with 24 other divers on board.

Nobody on the boat knew. It took about two days for anyone to find out. Their bag, wallet and passports were still sitting on the deck.

The story went round again this week after a viral post about it passed 1.6 million views. The replies were full of the same questions. How did a boat leave without them? How did 24 other people not notice? And did the couple really write a note?

How does a dive boat leave without two of its divers?

The Outer Edge took 26 divers and five crew to St Crispin's Reef, about 35 miles north-east of Port Douglas. The Lonergans had around 160 dives between them. They were not beginners.

After the third dive, the crew counted heads before the boat moved off. The count looked fine, and it was wrong. Another couple had left the water and climbed back on board, and that made the numbers look complete. That is how Undercurrent, a US dive magazine, reported it in 1998.

The trial in 2000 told a messier story. Dive master George Pyrihow said he could only find 24 of the 26 people. He said he was told to add two swimmers who were still in the water. The skipper, Jack Nairn, denied that conversation. He said he would have ordered a recount.

Other crew could not remember who counted heads after the first two dives. They said it was normal to assume a count had been done once the engines started.

Think about that. The only check between two people and the open ocean was a habit.

When did anyone realise they were missing?

Late on Tuesday 27 January. That is about two days after the boat left the reef.

A crew member spotted some of the couple's things still on board. Police checked the hotel, but the Lonergans had never come back. A coroner later criticised the 50-hour delay between the boat's return and the call to police.

The whole timeline is below.

Dates for the later items come from news reports and the Undercurrent archive.

Photo: Robert Linsdell from St. Andrews, Canada / Wikimedia Commons, CC BY 2.0

How big was the search for Tom and Eileen Lonergan?

Huge. It covered about 3,200 square nautical miles. Police used 17 planes, two helicopters, navy divers and private boats.

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They found nothing and called it off after three days. They said currents could have carried the divers far away and that debris from a cyclone made them hard to spot.

The search started again on 6 February when Tom's buoyancy vest washed up north of Cooktown. More gear followed, including Eileen's fin and hood. Police ended it on 14 February. The bodies were never recovered.

Did the Lonergans really write a message on a slate?

Yes, and it is the part that chills people most.

In July 1998 fishermen found a dive slate, the plastic board divers use to write underwater. Police tests said it had been in the sea for months. They said it was not a hoax.

It is reported to be in Eileen's handwriting. One transcription reads: "We have been abandoned on A[gin]court Reef 25 Jan 1998 03 pm. Please help us to rescue us before we die. Help!!!" Other reports give the wording a little differently.

The slate is dated Monday 26 January at 8 a.m. So they lasted the first night.

Notice one more odd detail. The slate says Agincourt Reef. The boat's dive was reported at St Crispin's. Reports do not explain why.

What did the coroner say, and why was the skipper not convicted?

In October 1998 coroner Noel Nunan said Nairn was responsible for the deaths. Nunan said he did not check the dive master's log or make a head count before turning for shore. Nairn was charged with manslaughter.

At trial, the case looked different. The defence said nine witnesses had seen the couple in Queensland after they vanished. A skipper on another boat said he heard an American accent among his passengers the next day. The defence argued the couple might have faked their deaths.

Nairn was found not guilty. Later summaries say his company, Outer Edge Dive, pleaded guilty to negligence, was fined and closed down.

Photo: Bahnfrend / Wikimedia Commons, CC BY-SA 4.0

Did Tom and Eileen Lonergan fake their disappearance?

This is the theory that will not die. It grew from two diary entries.

About six months before the dive, Tom wrote that his life felt complete and he was ready to die. Sixteen days before they vanished, Eileen wrote that her husband had a death wish. A Sydney newspaper reported the diary claims in 1998.

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Tom's sister rejected the suicide idea. The family said nothing at all had pointed to a problem.

The coroner threw out both a staged disappearance and a murder-suicide. He said they most likely drowned, or were taken by sharks, in the two or three days after being left. Online, many people still say the story smells fishy. They point to the sightings and the diaries.

Others point to the slate. If it is real, the couple were alive and begging for rescue.

Is the story behind the movie Open Water true?

In outline, yes. The 2003 film Open Water has a couple left behind by a dive boat after a bad head count. It was inspired by the Lonergans.

Photo: via X / @creepydotorg

The film adds sharks and a clear ending. The real case has neither. Nobody knows what happened after 8 a.m. on that Monday.

If you like stories of people alone at sea, read how four men rowed 56 days across the Atlantic, or how divers found 6,511 unbroken Roman dishes on the sea floor.

Do dive boats count heads differently now?

Yes. The coroner recommended a mandatory lookout and a way to check that every diver is back on board.

Queensland then brought in tougher rules. Reports say captains and dive masters must confirm head counts independently. A later summary says divers must sign when they enter and leave the water, two crew members must count, and the skipper must sign that he has seen both counts. Check current Queensland rules before relying on any detail.

Divers in the replies say many boats now read out names, not just numbers. A name can be checked. A number can hide a mistake.

What was happening on the boat while the slate was being written?

Nothing.

The slate says 8 a.m. on Monday. At that hour the Outer Edge was back in port. The planes had not been called. The police did not know.

Nobody would ask where the Lonergans were until late Tuesday. By then, if the slate is right, they had already spent more than a day in the water.

Someone held a pen in the open sea and wrote down the time. For roughly the next 40 hours, the only people on earth who knew they were missing were the two of them.