I went free diving with a former Navy Seal - he said two slow breaths trying to fully empty your lungs each time, then take a deep breath and hold. Actively hyp

I went free diving with a former Navy Seal - he said two slow breaths trying to fully empty your lungs each time, then take a deep breath and hold. Actively hyperventilating, especially if you're going deeper than 2 ATM (~10m/30ft) and your risk of a shallow water blackout goes way up.