Regarding the divers' finding, or lack thereof, I wonder if the ship's erosion has anything to do with this. I heard on the news a year or so ago that the ship could be completely deteriorated within ten to fifteen years from then (iron in salt water for many years). What I mean by what I mentioned is, had the technology of 1985 been around after the wreck, would divers have found a gash before it deteriorated beyond recognition? I am by all means not trying to argue anybody's posts here. It's just a thought

. As for the sinking, I learned years back that the ship was designed to take three days to sink if it were to hit an iceberg head-on. This could be old news by now, but it's what I heard.
As far as the historical accuracy of the film goes, Cameron may have spent a lot to get the details straight, but there are still inaccuries in the film. These are the ones I've noticed:
*The captain was not a passive guy in real life, and he had instructed Murdoch on what to properly do (hit an iceberg head-on if unavoidable) in the event the ship would approach an iceberg before he went to his quarters to sleep. The movie portrayed the captain in a rather nonchalant manner.
*The captain never gave the president of the ship-building company permission to increase the ship's speed. The president went behind his back and made the order; therefore, he was responsible and not the captain

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*Murdoch only shot and killed one passenger before he took his own life, not two passangers.
*The film did not hardly emphasize on issues like thefts and male passengers dressing up as females and boarding the lifeboats. This made the environment of the Titanic seem a lot safer than it really was.
*Only four passengers survived the icy waters, not six (five if Rose is not counted).
*Many passengers died 'cuz the crew never woke them up. They were still sleeping in their staterooms when they went under

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*This one annoys me. Molly Brown was a tough as nails, very strong female in real life. The real Molly Brown never let the male crew member speak to her the way the film character did and let him get away with it. I understand she even threatened to knock him overboard. She was the only one who rowed the lifeboat all the way to the Carpathian (none of the other females helped), and her fists were bleeding when they got to the ship. She was not a big woman either, so I'm not sure if Kathy Bates was the best pick as far as physique is concerned. The real Molly Brown was petite, and she hardly looked any bigger than me (I'm 5'2", around 140 pounds). Molly Brown was tough, and I wish the film had made her character more true to the real-life person. She was the only one in her family who escaped being massacred and fled out of Ireland onto the Titanic. She survived that, then her and her husband's bankruptcy, and his divorce from her. She was a tough broad, more of an Annie Oakley than a proper female stereotype.
Now, the following is somethin' interesting that I heard years back, and I feel the inclusion of this would have made the film more interesting:
The Heart of the Ocean, aka the Hope Diamond, really was on the Titanic at the time of the sinking. The man who possessed it at the time was known as Jack Hope. It is believed this is where the official name of this gem comes from. Given the diamond's notoriety of casting curses (painful deaths) upon those who had possessed it, this would have been interesting in the film. Could the Hope Diamond have been the culprit? We'll probably never know.
On a final note, although it was sad that it took such a tragedy to give humankind a wake-up call, I don't think our practices on ships would be what they are today if it weren't for this incident. This called for laws to be established in the following that I can recall:
*Passenger and crew capacity is not to exceed the limit of the lifeboat capacity.
*All ships must have emergency flares on deck.
*The SOS operator may not sleep on duty (McBride and Phillips were doing so on the Titanic).
*The crew cannot board lifeboats until all passengers have been boarded, regardless of gender or class status.
*Crew must ensure all passengers have been recovered from staterooms.
*All passengers and crew must have lifejackets.
*By law, passengers and crew must undergo a mandatory emergency drill before the ship leaves port.
That's all I can think of for now, and I'm glad these laws and regulations have been established so hopefully history will not repeat itself.