**WE REFRESH THE AIR WITH A SCUBA TANK**
Q. Isn’t this dangerous?
A. Yes!
The biggest danger is something called Pulmonary Barotrauma. That basically means over-expanded lungs. If you take a breath in the room the air you breathe in is compressed (because of the weight of the water above you). If you hold that breath and swim to the surface the air will expand in your lungs and can cause catastrophic damage or death. ALWAYS breathe OUT when ascending. ALWAYS.
Other dangers include: entanglement, concussio