I have been practicing Emergency Ascent for OOA situations. Drill is to take your second stage out of your mouth (to simulate an OOA and ascend to the surface while blowing small bubbles and within a max ascend rate of 18 meters per minute (60') per minute. (yes i know the regulator schould stay in your mouth, but this way i can't take "cheat" breaths) I have been practicing these ascends from 25 meters (80 '), and they are suprisingly easy. You are convinced you will run out of air but there was always enough air inside my lungs to continue to blow bubbles. I am practicing this to retrain my old 3* CMAS standards (before there was a 4*) where we had to do this once from 100 feet. ( I am one of those guys who still have their max air depth qualification of 60 meters or 200 feet ( ON AIR!) Any of your guys engange in similar deep OOA emergency ascend training?