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The sinking of the Titanic will forever be a cautionary tale of the excesses of pride and a lesson in never underestimating the might of our oceans. The luxurious cruise liner, dubbed "unsinkable", sank to a watery grave on 15 April, 1912, after hitting a hidden iceberg. The accident claimed 1,500 innocent lives.

In 1985, Dr Robert Ballard, an oceanographer and marine biologist with the Woods Hole Oceanographic Institution, found the remains of the Titanic. He recorded her coordinates as being 41o43'35" N, 49o56'54" W (the stern section); 41o43'32" N, 49o56'49" W (the boilers); and 41o43'57" N, 49o56'49" W (the boilers).

The point was that not only were the two ends of the ship found nearly 2,000ft apart, the wreck was discovered some 13.5 miles from her last known location. Since then a number of studies have been undertaken on the subject, whether for academic, investigative or treasure-hunting reasons.

One such expedition was the 2010 study, led by National Geographic. The study used an autonomous underwater vehicle, a camera mounted on a torpedo-like structure, to create a seafloor photo mosaic of more than 130,000 images.

James Delgado, the head archaeologist of the expedition and the Director of Maritime Heritage at the National Oceanic and Atmospheric Association (NOAA) felt the Titanic "held no more secrets" after that expedition.

"Just below the surface in this scientific coldness is an intense passion for this ship. When I first came to Wood's Hole in 1987, I was only interested in pure science of the deep sea. But, as I began to know Titanic better, I realized that there are thousands of stories at that spot in the middle of the ocean. It worked its way into my work, my mind and my soul," David Gallo, the Co-Director of RMS Titanic Inc.'s 2010 expedition said.

The Titanic was, in its time, the world's most luxurious ship... and it met with the greatest tragedy of all times. In memoriam, this year another cruise ship, the Balmoral, retraced the voyage of the Titanic and conducted a memorial service at the same spot where, a 100 years earlier, the ship sank.

The National Geographic has published exclusive and rare photos of the Titanic's underwater expeditions. See them below: