the divers wear vulcanized rubber suits and full face masks. >> you don't want the water to get on your face, especially your eyes, nose, mouth, ears. >> you don't even want this water in your ears? >> you don't. >> there is also a strong current that stirs up the bottom. it's so brown, so murky, the divers almost blindly have to pat the bottom, feel the underwater pier abutment. it's a training exercise to search for explosives. it's very slow work. but eventually they do find this limpid mine. it's just a training tool, but it would have been powerful enough to destroy the pier. searching the harbor isn't exactly pleasant. with the sewer plant next door, the water here is contaminated. >> don't touch your face or eat anything. >> lovely new york water, isn't it? >> the nypd, a police force that after 9/11 became a powerful, some say, intrusive, counterterrorism division. coming up, the nypd keeps a close eye on the streets of new york city. >> if i put on a black overcoat, walked around for half an hour, do you think in three days you would be able to find me? >> we would definitely be able to find you. they gave me this pantene called breakage to strength. [ female announcer ] the keratin protection pro-v system helps prevent then repair split ends. zero fear of breakage, 100% more strength. no regrets, just health. i'm not giving up the heat. [ female announcer ] the breakage to strength system from pantene.