that's where we found bob ballard. >> robert ballard: okay, on the rise. logan: thank you, dr. ballard. >> ballard: please, welcome to the "nautilus." >> logan: his ship, the "nautilus," never sleeps. ballard and his team have been out here for two weeks hunting for shipwrecks-- a 17-man crew of archaeologists, scientists, and engineers working in shifts around the clock. >> ballard: we're here to find lost chapters of human history, chapters we've never read before. >> logan: how many shipwrecks do you think are down there? >> ballard: in this area, i'm sure there's hundreds, if not thousands, along this coast. >> logan: that have never been seen? >> ballard: never been seen. >> logan: the "nautilus" is specially designed for deep-sea exploration, armed with state- of-the-art electronics and navigation systems. ballard's team uses sophisticated underwater sonar to guide them to possible wreck sites they call targets. >> ballard: there's a target, for example. >> logan: that little dot? >> ballard: that little dot. >> logan: could be anything? >> ballard: e