During deep dives, the tolerance to carbon dioxide enables Sperm whales to dive to depths of over one thousand metres in order to hunt the giant squid. This is an ingenious process. The ability to dive deep means that the whales can avoid the competition for food that has driven so many creatures to extinction over the history of our planet. The large food source in squid provides survival free from competition. Whales show no sign of carbon dioxide toxicity that plagues divers whose breathing technique is less than perfect.
Cetaceans are two to three times as efficient at removing oxygen from inhaled air.
Humans only use one fifth the oxygen in air that is inspired. That is eighty percent of the oxygen is exhaled. This limits our breath hold capability. Whales and dolphins slow down their heartbeat when they dive deep. This is known as bradycardia.