The cetacean holds its breath under water, breathing only at the surface, so there is not a constant supply of new pressurized air to be dissolved into its body. Scientists think that the deepest diving cetaceans may actually exhale before diving so that they have less air in their lungs to be dissolved under pressure. Amazingly, when a cetacean dives deep, under tons of pressure, its lungs actually collapse because there is no new supply of air to pump them up. Whales don't have to worry about excessive nitrogen getting dissolved, compressed and then expanded in their bloodstreams. The air the whale goes down with is the air it comes up with.
Whales also have more myoglobin, the oxygen-carrying pigment in the muscle.
The oxygen-holding capacity of the muscle and blood is another factor in the whale's ability to perform long dives. A. Scientists are developing technical means with which to track humpback whales, including radio tags and satellite tags. Also, the marine environment is extremely harsh and dangerous to electronic equipment. Work progresses in this area. This site has funded tagging projects on a variety of cetacean species.