divers are at. this is the pressure going through them. the main air, stand by air. emergency air, diver one, diver two, diver three which is your safety diver. reporter: he says the divers will probably be underwater for up to 80 minutes at a time. and then you get in a pressure university. this will have things to get in. it s going to be dark inside. a lot of things for divers to get snagged on. reporter: then there s the emotional component, right, you know there s going to be bodies down there? there s nothing worse than bumping into a bloated dead body in the water. reporter: he s sill haunted by the victims he s recovered, especially children. an emotion that divers will have to come to terms with. the way you get past it, you say i m helping the family. reporter: he tells us it could take weeks maybe months