it was a pretty entertainging show. They followed around a computer animated whale throughout the worlds oceans, and at the end of the show, we are taken to south pole. there the whale faces has only enemy of the deep. The Colossal squid (still undiscovered), The kraken, The stuff of fishermen's legends.
They put forth a very good reason why this giant beast can exist. and how they know it exists. First the know that something gigantic has been attacking whales when we see huge slashes from tentacles on whales that cannot be attributed to any known species. Science back it up by saying the reason why this squid can get so enormous (they beleive a female's body alone can grow up to fifty feet in length) Is because of the very oxygen rich water at the pole. This is the same reason why dinosaurs where so enormous, because there was so much more oxygen in the atmosphere. Im not sure why oxygen has to do with size in evolution, but apparenty it does.