How do whales stay underwater for so long without breathing?

Whales can stay underwater for extended periods due to their efficient use of oxygen and specialised physiology. Their lungs exchange up to 90% of the air in a single breath, compared to 15-25% in humans. They store oxygen in their muscles using myoglobin, a protein that binds oxygen tightly. Additionally, their heart rate slows during dives to conserve oxygen, and blood is redirected to vital organs like the brain and heart. Species like the sperm whale can dive for over an hour by utilising these adaptations.