Finding the Titanic, Bob Ballard tells you with a coy smile, was a piece of cake. Finding the origin of life of earth was dumfounding.

Ballard, 72, is the earth scientist and renowned undersea explorer maybe best known for locating the legendary "unsinkable" liner sunk by an iceberg, that inspired the widely popular movie. He spoke and was presented the Environmental Stewardship Award on Thursday at the eighth Annual South Carolina Aquarium Conservation Gala. He talked beforehand with The Post and Courier.

In the 1970s, earlier than the Titanic find, Ballard stumbled across hydrothermal vents deep off the Galapagos Islands.

The vents teemed with never-seen-before marine life like 8-feet-long tube worms that carry a pint of blood, even though they were too far down for life to be considered possible. They are now thought to be a likely source of all life on the planet.

"We were used to (seeing) a desert. Then to see this oasis with all these animals," he said, letting his jaw drop to show his reaction. "Clearly, that's where life began on the planet. But more importantly, that's where planets reproduce." The vents are huge, gaping cracks found everywhere tectonic plates separate, he said. "When you calculate the number of critters in these cracks, it's 10 percent of the biomass of the planet."

Ballard is a dapper man comfortable with his fame, if a little uncomfortable in the tux he wore for the gala. He is as ardent as he is soft-spoken. He has that coy tease and thinks like a researcher. He grabs a pen and paper to graph or illustrate his points rather than try to explain them.

He found not only the Titanic, but also the German battleship Bismarck, John Kennedy's PT-109, and in the Black Sea an embedded ancient boat with human remains still aboard.

He kids that he finds marquee vessels to get money to support exploring the ocean floor. He has made 140 expeditions.

The hydrothermal vents already had made his name when Ballard found the RMS Titanic in the North Atlantic. The story behind that search is even more fascinating than the find.

"The Titanic was a cover," he said. The Navy sent him, a former intelligence officer, to locate two nuclear submarines that sank in the same broad area - one with nuclear weapons aboard - and test for radiation leakage. The Titanic "search" provided the Cold War era cover story he needed. His interest in the Titanic had been piqued by failed earlier attempts; the Navy gave him 12 days after the subs were found. Ballard discovered the subs had imploded, leaving debris fields splayed across a wide span by the ocean current, and heavier material like the reactor buried in the ocean floor. No radiation was detected in sea creatures nearby. The debris field, though, gave him the clue he needed: Maybe earlier searches hadn't found the Titanic because it too imploded into too many pieces.

He started from where the location where the rescue ship picked up the lifeboats, tracking back against the current drift.

"What you do in a search is go to (start) where you know it's not," he said. He looked for a scattering of smaller debris and craters where the heavier ones sank into the bottom.

"On the 9th line (pass) we found the debris field. Piece of cake," he said with that smile. "Yeah, we really are good."

Ballard is still at it. He leaves in June to explore the American ocean floor that comprises 50 percent of the country's land mass but is relatively unknown. His stewardship message is plain:

"I'm of that school of thought that the earth is a creature, and you're watching it respond (to human pollution stresses) right now," he said. "It's very angry. It may kill us."

Reach Bo Petersen at 937-5744, @bopete on twitter or Bo Petersen Reporting on Facebook.