Is breathing completely involuntary

No Not not COMPLETELY but mostly is ya

If you count your body as a whole, breathing is a completely involuntary action. All we can do is stop, or interrupt, the primary process for a short time. The way we all know to breathe is, of course, through our mouths and noses using our lungs, which is an involuntary process that the subconscious brain takes care of ever when we don't think about it. On top of that, your entire body is breathing through your skin as well. Every pore takes in oxygen, that is one of the reasons skin painting CAN be deadly; it blocks off the pores of your skin from oxygenation.