The Flannan lighthouse was a lighthouse located on Eilean Mòr, an island off the west coast of Scotland. It was manned by three people at a time, in a rotating schedule with a fourth man who was off.
At the time of the mystery in December of 1900, the three men were James Ducat, Thomas Marshall, and Donald McArthur. They were dropped off at the lighthouse as usual for their stint as caretakers.
For most of this time, there was nothing unusual. However, in mid-December a passing ship observed that the lighthouse was unlit, which was highly irregular and could be a serious problem.
On December 26, 1900, the Hesperus, the ship bringing the relief keeper approached the lighthouse. There was no sign of life. There was no flag flying; boxes meant to be refilled with provisions were not evident. The ship’s Captain Harvie blew the signal whistle and fired off a flare to try to get attention. There was no response.
The relief keeper Joseph Moore went ashore to investigate. He could find no sign of any of the men. The lamps were in order. The beds were unmade, the clocks had run down.
They found a set of oilskins. Two other sets were missing. Some accounts mention that a chair had been overturned; however, this does not appear in all reports.
There was evidence of some serious bad weather, including a damaged toolbox well above the level of the sea. Evidently an unusually large wave had broken it apart. Aside from that, there was nothing else to be found.
Much has been made of this mystery. Many of the stories contain embellishments about a severe storm threatening the lighthouse itself; one many crying, one man praying, and so on. The problem with these accounts is that they don’t agree with the facts. There had been no severe weather during this time. There was nothing to suggest that anyone had been crying or praying.
What most likely happened was that two of the men went out wearing oilskins to protect them against the weather. At some point, the man remaining in the lighthouse must have become aware of the men encountering danger. The third man ran out to help, neglecting his oilskin and violating the rule that the lighthouse must never be left unattended. Clearly this was an emergency.
What the men encountered is up for debate. I would think a rogue wave could explain it. Somehow a wave came, slammed into the island, and possibly carried off the men who were already outside. The third man ran down to help, and was also carried away.
What probably didn’t happen was some sort of sea monster picking the men one by one; or aliens; or pretty much any of the dozens of exciting, but nonsensical explanations.
Captain Harvie, in his report on the situation, agrees with my explanation. That’s good enough for me.