How do whales dive nearly 3 km deep with air in their lungs

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I assume that the air in their massive lungs produce a lot of buoyancy so how are they able to accurately control their depth in water?
Thank you!

In: Biology
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They’re built a little more sturdy, with reinforced airways and such. Additionally, they don’t simply hold their breath the way humans do (with full lungs and all).

As they dive, their lungs collapse which forces air away from the gas exchange (between blood and lungs) organs.

So how can they stay underwater for so long if they don’t store oxygen in their lungs during a dive?

They have massive specific blood volumes….about 3-4 times what terrestrial mammals do (so per kilogram of weight, they have 3-4 times as much blood as humans). In addition, they have about twice the concentration of hemoglobin (the oxygen-transport protein in blood) as humans do. Lastly, they have an absurd concentration of myoglobin (oxygen storage protein in muscle), about 10 times more than humans.

Add that all together and you have a creature whose body has a significantly higher ability to store oxygen per pound of mass *even if not stored in the lungs*, than terrestrial mammals are capable of.

They can effectively push all the oxygen out of their lungs, but still have a much higher capacity for holding their breath than humans attempting to do the same thing.

[(source)](https://www.scientificamerican.com/article/how-do-deep-diving-sea-cr/)

Air compresses with depth. At 33 feet below sea level, the air in their lungs is like half the volume of sea level. So buoyancy goes down a lot with changes in depth. Once they’ve gone down a short amount, the buoyancy of the air in their lungs becomes negligible.

Great answers I have a secondary question, why don’t Whales or dolphins get the bends? What about the nitrogen?