Ballard has made some of the greatest deep sea discoveries of our time. He found the legendary German battleship, Bismarck, three miles below in the Atlantic.
He showed video of the massive ship to Logan, pointing out the guns. "And we almost hit them because we came in very low on the deck - and all of a sudden, first thing we saw of the Bismarck was a barrel of a gun coming right at us."
He tracked down what is believed to be the remains of PT-109, commanded by John F. Kennedy in World War II.
But the one that made him famous was the Titanic. For 73 years, the massive ocean liner sat two miles down, more than 12,000 feet of pitch black water, eluding the world's top undersea explorers until 1985, when Ballard came along.
Ballard showed some of his personal videos of the wreck, including footage of the captain's bathtub.
He told us what it was like to come face to face with the world's best-known shipwreck. "We turned the corner and there it was right in front of us!" he remembered. "The bow was 60 feet into the bottom."
"Up at the very edge, because it hit with such power, and it bulldozed so much. We rose along the side of the ship and our lights were hitting the portholes, and they looked like eyes. A hundred eyes, like the people who died, it looked like people looking at us," he explained.
But finding the Titanic really wasn't his mission. "Well, it was my mission, but I had to get it paid for," he said.
The Navy had tasked Ballard with a secret mission to map two nuclear submarines lost in the Atlantic during the Cold War, the USS Scorpion and Thresher. They didn't want the Russians to know what they were doing.
"Because if you told the Russians, 'Hey just follow me,' they'd put a satellite over the top of me and they'd see me go out and they would see me stop. And the moment they saw me stop…I just told them where the submarines are," he explained.
The cover for his Navy mission was that he was actually searching for the wreck no one else could find: the Titanic. Three other expeditions had tried and failed, even though they had months to search; Ballard had just 12 days.
Asked how he got around that, Ballard told Logan, "By cheating. I basically didn't do the search pattern the way they had done it. See the traditional approach to searching for something in darkness, cause you can't see, is use a sonar. And you lower the sonar down, and you tow it back and forth, and you mow the lawn. And that's what all three of them had done. And I went, 'Well, clearly that's not working.'"
So Ballard used what he had just learned investigating the Navy subs: that when a vessel sinks, the wreckage is carried by the current, leaving a trail of debris like a comet. Applying that to the Titanic, he decided not to look for the ship itself.
Instead he searched for the trail of debris that he estimated stretched over a mile, a much bigger target.