HERC AT WORK: Meet Hercules, also known as Herc. This submersible, or underwater craft, helped Bob Ballard explore the Titanic wreckage in 2004. Herc dived more than two miles below the surface to explore the lost ship. The sub sent digital images and other information up to the explorers. Photograph from the Institute for Exploration/University of Rhode Island © 2005 National Geographic Society. All rights reserved.