New toy I want

Going to need a bigger descender 

Makes sense now!!! That's why you look like that you like to scuba!

I free dive quite a bit, this thing has a 25 foot range. Never had a scuba class so I don't understand the danger

And therein lies the problem.
Great cartoon. Perfect explanation w/o any words.
Here's hopefully a simple explanation in over simplified terms.
Lets say at the surface a molecule of air is the size of a tennis ball. Your lungs will hold 8 tennis balls of air at the surface.
You take your breath of air at the surface (8 tennis balls) and as you descend the the pressure of the water squeezes those tennis balls into the size of BBs. Your lungs also get squeezed so they too will only hold those 8 BBs.
Now as you come to the surface and the pressure decreases those BBs expand back into tennis ball size and your lungs expand at the same rate and will still accommodate the 8 tennis balls.
You started with 8 and you ended with 8 and your lungs compressed and expanded the same as those 8 original molecules.
Now lets say you are breathing air 25 feet below the surface. Those molecules at the surface started out as tennis balls but by the time they reach you, because of the water pressure, they are BB size when you breathe them.
You inhale a full breath, as much as your lungs can take in, but you are inhaling BBs, not tennis balls.
Now instead of filling your lungs with 8 tennis balls you have filled your lungs with 256 BBs.
Here's where the danger resides. IF you hold your breath and swim to the surface each one of those BBs will expand to the size of a tennis ball as the water pressure decreases.
Remember earlier at the surface your lungs could only hold 8 tennis balls? What do you think will happen when those lungs try to hold 256 tennis balls? KABOOM! You're dead.
YOU MUST exhale the entire way up if you are not breathing. If you are breathing you need to slow down your assent. Stay just below one of your small to medium sized bubbles all the way up. This way the molecules you are exchanging are changing in accordance to the pressure around you.
I never understood how this works until I did my first free assent while SCUBA diving.
How the hell can I exhale all the way to the surface from 40 feet below?
Best way I can describe it is like the clown and the handkerchief trick. Like the handkerchiefs just keep coming and coming, so does the air you are exhaling. As those molecules expand they seem to pour out of your mouth non stop.
Bottom line: NEVER HOLD YOUR BREATH IF YOU GOT THAT BREATH FROM BELOW THE SURFACE! PERIOD!

So what you're saying is that PV=nRT? 

So what you're saying is that PV=nRT? 

He has dense gas... 

I think I'm so awesome for posting this so everyone could get an education including me now no one out of the 5600 members will buy one of these. And they'll all live now. I'm a hero I just saved so many lives thanks to totes explanations