marshes and shores once covered in oil. today from our boat we spot two dozen workers wearing face masks, shoveling, working on a stretch of beach. we pull up to take a look. how you doing? doing good. drew griffin with cnn. nice to meet you, sir. this is philippe cousteau? >> stay away from the hazardous material. that's the cleanup site. >> reporter: the hazardous material turned out to be bp's oil. a 90-foot long 30,000-pound tar ball. we tested one and it matched the oil from the spill. five years later, there is still oil. oil in big enough clumps that it needs to be dug up by a crew like this digging down 30 inches trying to take it and remove it. >> the pockets of tar mats that exist are in areas known to us