Robert Ballard is a former US Navy officer and a professor of oceanography, who is most known for the discoveries of the wrecks of the RMS Titanic in 1985, the battleship Bismarck in 1989, and the aircraft carrier USS Yorktown in 1998.

According to Robert Ballard, who found the infamous ocean liner, discovery of the Titanic was a result of a secret US Navy investigation of two wrecked nuclear submarines, U.S.S. Thresher and U.S.S. Scorpion which sank in the 1960s. “The Navy is finally discussing it,” said Ballard, an oceanographer at the University of Rhode Island.

Ballard met with the Navy in 1982 to request funding to develop the robotic submersible technology he needed to find the Titanic. The Navy was interested in the technology, but for the purpose of investigating other wreckages.

Since his technology would be able to reach the wrecked nuclear submarines, Ballard agreed to help. But he was never given explicit permission to search for the Titanic.

They finished before they were due back, so the team spent the extra time at sea looking for the Titanic – and found it.

Reference:

http://en.wikipedia.org/wiki/Robert_Ballard