Apparently James Cameron's Titanic obsession is genetic. His brother Mike's engineering firm, Dark Matter, custom-built two remotely operated vehicles to probe the Titanic's multitude of staterooms, stairwells and cargo spaces. Brother James then used these ROVs to help shoot the 3-D Imax documentary, Ghosts of the Abyss, which opens April 11. We spoke with the brothers about the ROVs, the Titanic and why the Navy is interested in doing business with them.

Popular Science There are plenty of ROVs out there. Why build your own?