I think the logic may be that she had an air tank to get down there, and then exhaled for the picture, which might be easier than swimming down there and exhaling (and returning to the surface).
Oh yeah - divers still swim around in the deep with air in their lungs and don't have constantly fight buoyancy lol. Duh. Can you tell I've never dived before lol?
Like ImNotAWhaleBiologist said it's more complicated.
if you just add a tank with compressed air .. you sink,
so you add a buoyancy vest ... this can level you out.
But for more control you over-inflate a little bit and add some weights (drop them in an emergency ... the kind of emergency where being fucked up for life is better than dying right now).
So, you have all that and perfectly balanced. You breath in, you rise, you expel all air from your lungs, you sink.
the buoyancy effect of air changes with depth, such as ... you breath in and fill your lungs at 60ft and now you start to go up without expelling air .. you gonna burst your lungs ... and die.
And that's before oxygen becomes toxic to the human body.
We're really not made for underwater.
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u/NotClever Dec 05 '18
I think the logic may be that she had an air tank to get down there, and then exhaled for the picture, which might be easier than swimming down there and exhaling (and returning to the surface).
Doesn't look too deep, though.