and silt, how challenging is it for the search? >> reporter: don, you can see we're out on the boat, i want to introduce you. just -- the indian ocean we've there.how rough it is to work can you put it in perspective for us? >> from a sonar perspective it is actually a good environment, it is very deep, you want to get the sonar down very deep. but the complexity of the depth, to get the sonar down deep you have to put it on the auv. it has to have navigation, communications and dive down deep. it is really complex. >> let's go and look at the data that they're likely getting from a side scan sonar. >> so this is an example of a side scan data. the sensor travels through the water, hits the sea floor and then continues to go. based on that you can build up an image of what is on the bottom. we just passed over a pipeline. >> so does this mean, something