>> alfonsi: ...and oxygen reserves are drained.ims the lives of about 60 recreational free- divers each year. that's something the world of competitive free-diving has worked hard to prevent, by adding safety divers, underwater monitoring, and doctors at every event. there has only been one death during a competition in the last 20 years. have you ever had a blackout? >> molchanov: i had. when i was a beginner free-diver i would be very stubborn and i would push it to the end. i wouldn't listen to the signals my body gives to me. and now i have much better awareness of what's going on. >> alfonsi: when i was sitting out there watching you guys dive the other day, and i was watching the competitors, a lot of them would come up and they would gasp for air. and you emerged from the water, and you smiled. >> molchanov: i think that's an essence of being able to do really deep dives and records. like, it's very hard to do those deep dives being stressed, and it would look from outside that it's really easy. but it's not. of course, by t