bluefin because this autonomous vehicle is used to working in deepths several miles belet surface. the bluefin 21 can dive about 2 1/2 miles but flight 370's wreckable in the indian ocean may be deeper than that. it takes about two hours for the bluefin to reach the bottom, where it can operate for another 16 hours. it scans the ocean floor as if it's mowing a lawn, aye icing side-scan sonar, which identifies objects that stand out from the seabed. when it's working with the side scanners it is not actually taking pictures, right, it's measuring sound? >> it's actually converting sound to electricity and then turning that electrical value into numerical value, then turn it into an image a. >> reporter: when it returns to the surface, scientists download the sonar data to computers. the results may look something like this. >> looking at here, for example, this is a shipwreck in boston harbor, you can see how it's different than the area around it, you can see there's parts of