Whales suffocate to death; they don’t drown.
Human breathing is controlled by the autonomic nervous system. We have to hold our breath on purpose to stop ourselves from automatically breathing. This makes us passive breathers. Whales, however, are active breathers. They must choose to inhale which is why they can sleep without sucking in air. When they get too old, sick, or weak to surface, they suffocate.
Bonus fact: whales can’t breathe through their mouths; it goes straight to the stomach. The blowhole is the only respiratory tract.
Bonus bonus: a blue whale’s throat is so small it could choke to death on a grapefruit.
