Underwater Obstructions News Today : Breaking News, Live Updates & Top Stories | Vimarsana

Them so divers don't get hurt. >> underwater obstructions are a concern. we tend to fly the auv at about a 45-meter altitude of the bottom. keeps us usually out of the way of obstructions. >> reporter: these types of searches can take months or years. but the payoff is high. wreckage that gives clues about what happened, data recorders and the thing that matters most, the fate of the people on board. rosa flores, cnn, new york. >> so that's an idea of how it's going out there. but right now, chad myers, bring you in. you have done math looking into the search area. but what i really wanted was...

>> the smaller ones are only going to down to 5,000 feet. the next is a larger device that's 15 by 25 feet. it's very large because it adds a lot of battery capability and hydraulics capability. >> reporter: the auvs can go as deep as 20,000 feet sending acoustic pulses to the sea floor to find debris and then maps are drawn to guide search teams. they can even find things up to 300 feet under the sea floor. the search zone needs to be narrowed down first. this auv can only search eight square miles a day. it would take four days to search an area as big as manhattan. the equipment works aroun...