Mary Celeste (pictured here) was an American brig with a crew of eight and two passengers – the master's wife and infant daughter – which embarked on her fatal voyage, from New York to Genoa, in the autumn of 1872.

Her story, as it's usually told, emphasises several aspects that add to the air of mystery that still surrounds the disappearance of the ship's entire complement. The master, Benjamin Briggs, was highly experienced and highly respected, a man of good character and strong religious beliefs. The ship herself was in good condition and had been manned by a sober, reliable crew, made up of a mix of New England seamen and Germans. And, when she was found by the men of another sailing vessel, the Dei Gratia, she was alone on the sea, and, as you mention, still perfectly seaworthy and sailing on in calm conditions.

A lot of the mystery that surrounds the Mary Celeste originates from what secondary sources report that the men of the Dei Gratia found when they rowed over to the Mary Celeste and went on board. As generally told, these details include:

The brig was well-built and reliable and was found with her sails properly set, a hot, half-eaten meal still sitting in the cabin, a watch, not yet wound down, still ticking in the master's berth, and a full bottle of cough medicine, with the cork out, sitting unspilled on a table.

There were no signs of any sort of hasty departure and the ship's boat was still hanging in its davits.

Plainly, had all these details been accurate, the mystery of the Mary Celeste would indeed have been very difficult to solve. But the popular story of the ship is not correct at a number of key points.

One thing to bear in mind is that a significant number of the weirder aspects of the mystery turn out to have their origins in the high-handed investigations of Frederick Solly Flood, the lawyer in charge of the ship's salvage claim, or in fictionalised versions of the story, not least Arthur Conan Doyle's short story "J. Habakkuk Jephson's Statement" (1884). It's thanks to Conan Doyle that the ship's name is almost invariably incorrectly given, as Marie Celeste, and the date of her voyage as 1873, not 1872.

Other aspects of the story, which are important to the various attempts that have been made to provide a rational explanation for the crew's disappearance, would include:

The ship and her cargo were quite heavily insured, for a total of almost $55,000

She carried a cargo of 1700 barrels of raw alcohol

The captains of the Mary Celeste and the Dei Gratia were known to one another.

As to the state of the Mary Celeste when she was found, the truth is that she was sailing under very short canvas (jib and foresail) – that is, almost all of her sails were furled – that the running rigging was badly battered, that barrels of fresh water on deck had shifted, and that the cabin interiors were soaking wet, all indicating that she had encountered a heavy storm. In addition, two of the ship's hatches were off, the ship's clock had stopped, there was no food on the table and indeed the plates in the kitchen had been secured as if for rough weather, and the last entry in the log was dated to the morning of 25 November, nine days earlier; it gave a position about 600 miles from where the ship was found.

Most importantly, the *Mary Celeste'*s papers, navigation instruments and ship's boat were missing. Hence it was clear that the crew had deliberately abandoned ship – apparently very hastily indeed, because most of Briggs's charts, together with the men's oilskins and pipes, had been left behind. The true mystery of the Mary Celeste thus lies not in explaining how 10 people could literally vanish, apparently only moments before their ship was boarded by would-be rescuers, but in reconstructing a sequence of events that could plausibly have caused Briggs to have risked putting his wife and child, as well as his men, in a tiny boat in rough weather in the middle of the Atlantic, when his ship was in no obvious danger of sinking. There's very little mystery as to what happened to the people on board – their lifeboat was almost certainly swamped in heavy seas.

It's certainly true that no really clear reason for the ship's abandonment was found by the men of the Dei Gratia. The cargo was well stowed. There was no evidence of fire or of any sort of violence. There was a makeshift sounding line lying next to a hatch down to the hold, together with about three and a half feet of water down below – quite a lot, but not so much that the crew could not have drained it by steady use of the Mary Celeste's hand pumps – which were perfectly functional. The ship had not sprung a serious leak and was not in danger of foundering. Half a dozen barrels of alcohol – made of a different sort of wood to the rest of the cargo – were found to be empty.

A crew made up of men from the Dei Gratia took the Mary Celeste to Gibraltar and there lodged a claim for salvaging her. Their theory was that the original crew had miscalculated the amount of water in the hold and panicked. Other theories that were put about after the ship made port included Flood's claim that there had been mutiny and murder on board – he found an old sword in the master's cabin, and believed it had been carefully cleaned (presumably of bloodstains) with lemon juice, and located mark on the topgallant rail he believed had been made with an axe, plus what he took to be bloodstains on the deck nearby – and the idea that the master of the Mary Celeste had conspired with the men of the Dei Gratia to be taken safely off their ship and then to lodge a fraudulent salvage claim. Another popular suggestion was that the ship had been struck by a waterspout.

In secondary sources, many of them confused thanks to inaccurate reporting or the incorporation of purely fictional elements, we can find many wilder claims:

• that the people on the Mary Celeste had been snatched by a sea monster such as a giant squid

• that they had been enveloped in a gas cloud released by a submarine explosion, which drove them all mad and made them leap into the sea

• that one of the crew had descended into a religious mania and murdered everyone else before casting himself into the sea

• that the ship (which was actually found well to the east of the Azores, not too far off the coast of Spain) was a victim of the Bermuda Triangle

• that everyone on board had died as the result of a bizarre agreement to run a swimming race around the ship, which the remainder of the crew had chosen to watch from a jury-rigged platform at the bow (where identical indentations were found cut into both sides of the ship's rail). The platform was supposed to have collapsed, depositing the passengers and crew into the water with the swimmers, leaving the ship to sail on without them

As for Conan Doyle's story, it revolved around a statement by an alleged (but non-existent) survivor of the ship, who recounted how the rest of the crew had been murdered in a racially motivated attack carried out by an equally non-existent black sailor.

Once we separate Flood's real evidence from his errors and speculation, there is no real evidence to support the mutiny theory. Probably the most ingenious and likely solution to the mystery was first suggested by one of the Mary Celeste's owners, James H. Winchester, who hypothesised that leaks from the cargo of alcohol had generated gas that exploded when a man went down to inspect the hold carrying a lantern – thoroughly alarming the crew, who abandoned ship fearing that the entire cargo was about to blow up. In one interesting version of this theory, it was suggested that Briggs decided to vent the hold (accounting for the open hatches) while he and his men stood off the ship at a safe distance in the boat, which they tethered to the Mary Celeste with a rope; they were then cast adrift when the rope parted in a squall. In my own opinion, the idea that the crew mistakenly believed that their ship had sprung a leak and was rapidly filling with water (perhaps, as suggested above, as a result of a hasty and botched sounding of the hold) is also fairly credible, though it's hard to imagine how any sounding could have been so much in error that the crew imagined they had only a couple of minutes to escape before the ship foundered.

By far the best source for the case is Charles Edey Fay's The Story of the Mary Celeste, first published in the 1940s, which prints almost all the surviving primary sources and very ably discusses them.

Comparable "ghost ship" stories, involving ships found still afloat but minus their crews, are not hugely common, and several of the ones that do exist are very poorly reported or heavily fictionalised, but you might well enjoy looking up the details of two that remain mysterious: the disappearances of the crews of the Carroll A. Deering off the Carolinas in 1921 (which I wrote about here) and the Joyita in the South Pacific in 1955. The former is the subject of the semi-fictional Ghost Ship of Diamond Shoals by Bland Simpson, and the latter is convincingly dealt with in David G. Wright's Joyita: Solving the Mystery.