ocean? >> what you want to do first is to really map the entire accident scene. >> we spoke with peter goals, a former investigator with ntsb when worked on the recovery and rebuilding of twa flight 800 that crasheded after takeoff fr new york city. >> you document everything until you really get the information off the data recorder and the voice recorder. >> he says the site needs to be treated like a crime scene and mapping the debris field before removing objects is key to finding out what happened. then come the process of pulling up the giant pieces of debris from the bottom of the sea. >> you would have a number of lifting cranes and you would have teamed of divers. and the divers, of course, even working at 100 foot depth, you'll have to have decompression chambers. >> a slow process because divers with only remain at depth for short periods due to health hernz.