Dive Training magazine devoted gobs of their March 2002 issue to Free Diving. While the article is not on line, in their “No Dumb Questions” section, there is a related question that is answered. A quote from the response is here.
The full response can be found here. Third question down.
Whales exhale before diving. Watch a film of one and you see the spray (condensation from warm lungs to cold air) coming out of the blowhole just before they submerge.
With no air in the lungs, there is little nitrogen in the blood. What there is doesn’t cause the bends because it’s not under pressure to start with, so it never causes bubbles as the whale surfaces. Oxygen for diving is primarily stored in the muscles in myoglobin and not in the blood in haemoglobin. Whales take a series of breaths to pack the oxygen into the muscles, exhale and down they go.
Don’t know about seals/sea lions and other marine mammals.
I once watched a TV documentary on North Sea oil rig divers many years ago. They had microphones attached to their chests. As they surfaced from non-decompression dives, you could hear the nitrogen bubbling out of their blood stream into their lungs like opening a can of Coke. Scary stuff for an infrequent amateur diver like me.
Just checked the New Scientist archive. The record for human deep diving is 152 meters (over 165 yards in old money) and 7 minutes 35 seconds for breath holding. :eek:
Check here
Unless you breath out your nose…
I was wondering about this pressure problem with a hose (I used to be a lifeguard and I admit that I tried this, and can back up that it does not work). My solution was going to be adding a type of bellows with a one-way valve at the bottom of the hose. You would then use this to draw air down the hose and than again to force it into your lungs. Still not sure it would have worked.
But then the sheriff would find you because he saw the bubbles and all that hiding and breathing through a hollow reed was in vain. 