Survivors of the sinking of a Red Sea ferry carrying some 1,400 people have said that the disaster was caused by a fire breaking out below decks.
The al-Salam Boccaccio '98 was sailing in poor weather
Witnesses report that fire erupted about 90 minutes into the overnight journey from Duba in Saudi Arabia to Safaga in Egypt.
It is not clear where exactly the fire started - some say it was in the car deck, others in the engine room.
David Osler from the London shipping paper Lloyds List says a engine room fire would be more likely, although neither possibility could be ruled out.
The scale of the blaze is also unclear - survivors have spoken of the ship being engulfed in smoke and passengers running onto the decks wearing life jackets, begging the crew to turn the vessel around.
However, the captain made no attempt to return to shore, opting instead to continue on to Egypt while the crew tackled the flames.
Ships should be equipped with the means to put out a fire - especially important in ships such as the al-Salam Boccaccio '98 - a "roll on-roll off" (ro-ro) ferry with a large open space for cars, where fires can easily spread.
According to Mr Osler, methods for fighting ship fires vary according to the sophistication and age of the vessel, ranging from the use of inert gas to douse flames to hoses and hand-held extinguishers.
The al-Salam Boccaccio '98 was 35 years old and there are conflicting reports on whether it met all safety requirements.
Nonetheless, one UK expert on fighting ship fires, speaking on condition of anonymity, said that it was likely the ferry had sprinklers.
Normal practice in such an incident, he said, would have been for the crew to also tackle flames with hoses, pumping the water out to ensure it did not accumulate.
What seems likely to have happened in this case, the expert conjectures, is that the crew failed to remove the excess water allowing it to build up.
Rani Kamal, the surviving third officer on the ship, told the Arabic news channel al-Arabiya that "the ferry sank because of firefighting operations".
"Water flooded the garage [car deck]... and it pooled on one side. Then the water increased and increased until the ship listed sharply," he said.
According to the UK expert, in the kind of rough weather the al-Salam Boccaccio '98 experienced before it went down it would only take two or three inches (5-8cm) of water on the deck to set off a Free Surface Effect.
The Free Surface Effect is a phenomenon whereby a small amount of water inside the vessel starts slopping from side to side, making the ship rock.
As the water moves it gathers momentum, causing the rocking to become more pronounced.
The shifting water quickly makes the ship unstable, and can shift cargo and capsize the ship quickly.
Mr Osler says that the ferry's chances of surviving were further reduced by modifications made in the 1980s, when two more passenger decks were added.
Like the reverse of an iceberg, the vast majority of the ship was standing out of the water, with little below the surface to keep it stable.
Compounding the problem were the high winds on Friday, which may have further tipped the vessel, and reports that panicked passengers all ran to one side in bid to escape the fire.
Marine experts say that after foundering caused by the collision or grounding, fire is the greatest risk to a ship.
As a result crews are expected to be well trained and strict guidelines on how to deal with such incidents are outlined in the International Safety Management (ISM) Code.
Eyewitnesses say the ship sank in five to 10 minutes. Many people are believed to have still been below decks when it went down.
The tragedy was made worse by fact that the rescue effort did not get under way for at least seven hours after the disaster.
Even a small amount of water sloshing about below decks can seriously affect a ship's stability
As the vessel rolls, the water pours to one side which moves the ship's centre of gravity
If this moves beyond a critical point, the ship cannot right itself and will capsize