Submerged?

about blowing bubbles.... i think its quite normal that it happens long before they go up to inhale.

i did some rudimentary freediving on vacation. basically i see something interesting down there, and want to get there, without scuba diving experience or equipment, just swim fins for the feet. so you try to enrich your body with oxygen, then inhale, not too deep because i didnt have lead weights either, and then you go down. now after a while that air in your lungs turns bad, and for me this was the time to get back up, so you exhale, then go up. the thing is, when the air in your lungs goes bad and you cannot gain any more oxygen from that, you just exhale it. and depending on your physiology, you still have extra time after that.

you see that in many water-loving species that have lungs, like whales and seals and also aquatic reptiles like anacondas. they go down, stay down, exhale, stay down some more, then come up. you see the same in human freedivers that do it the natural way. the profesional record hunters are a different story because they use pure oxygen, so they exhale on the way up. but for people that just have fins and use regular air and that just want to hang around at 20 feet depth its normal, they exhale when the air in the lungs gets too bad, but still hang around a bit longer before they go up.

BPs are just like that. apparently they just have the evolutionary programming to get it right. so when they do the nose bubbles, it means they are maybe two-thirds done, but can still stick around for a little while longer. i dont have data on this, but i would not be surprised to hear that BPs can dive for really long times, their metabolism has advantages in this area.