coast of australia, the aerial search can last just a few hours at a time before pilots have to head back to refuel. >> that is really in the middle of nowhere. so they're working with weather patterns that can really hamper any operation, any sea operation. >> reporter: a nasa simulation shows currents and turbulence. these water conditions could push any debris further east and further apart. those objects, some of the strongest leads in this case, could be anywhere in a 15,000 square mile area. that's roughly the size of belgium. below the water's surface, a murkier picture. the sea floor sits more than 9,000 feet down. deeper than most submarines can go. the mid ocean ridge rising from it making the search each more difficult. >> the depth is a factor here. the terrain is a factor. describe what it would look like down there.