Save The Titanic National Geographic

More than 73 years after it had sunk off the coast of Newfoundland, Canada on April 15, 1912, killing over 1,500 of the 2,000 people on-board, the 1985 expedition found the Titanic after four previous attempts failed.

Find out when Save the Titanic: Treasures from the Deep is on TV. Episode guide, trailer, review, preview, cast list and where to stream it on demand, on catch up and download.

Dr Robert Ballard, professor of Oceanography at the University of Rhode Island and explorer-in-residence for the National Geographic Society was the co-discoverer of the wreckage.

To celebrate the 100th anniversary of the Titanic's sinking, the National Geographic television channel has produced a documentary about Dr Ballard's journey.

Veteran of more than 125 expeditions, he says the the team's presence in that part of the Atlantic Ocean was not primarily to find the famous wreck, but instead he was on a military mission.

At the time, Dr Ballard was a naval intelligence officer and was charged with locating two sunken US Navy submarines, the Thresher and the Scorpion. With the Cold War still rumbling the location of both nuclear submarines was a senstive matter, especially as the Scorpion was carrying nuclear weapons.

'My mission was to find those reactors and find those weapons. But we didn't want the Soviets to know that we were doing that or they'd put a satellite on us and we'd lead them to our submarines,' said Dr Ballard.

'And so we needed a cover and I suggested naturally the Titanic, because I wanted to find the Titanic. 688 fast attack submarines. And so we then went out and actually did our covert operations and then went and did the Titanic, but there was only a few days left.'

Save the Titanic with Bob Ballard is due to be broadcast on Monday, April 9 at 8pm on the National Geographic Channel.