football fields which sounds like a lot but really it isn't. tom foreman is live in washington. good morning, tom. >> hi, carol. we've been saying that once this goes under water it's going to be a much slower and more meticulous and cover a lot less ground. we had the towed pinger which was airline to go at a fairly good speed. now we're looking at the bluefin. yeah, this thing has to crawl along here. it's operating at a depth, carol, that is much lower than what is typically used for this. it can reach down to two and a half miles and it's going to be right at that range here where it's operating. typically you would see these a lot more on coastal shelf areas, carol, where it would be down 1,000 feet, something like that. in that circumstance they may be able to work a fleet of them, several working at once together, although that's rarely attempted, but at this level they get it down to its limit of performance and see if they can