And you think it was all legit. He is an illussionist, a magician, and a very good one at that too.
So do you think he was able to sneak out the bottom of the pool and grab a breath of fresh air without anyone noticing? All world record judges had a lapse in concentration?
Maybe he had a giant oxygen tank strapped to his back!!! The judges just didn't mention this detail?
Illusion is about misdirection...making you focus on something and while your attention is diverted something else is going on. For instance, when a card trick is being done, the magician says "concentrate really hard, and make sure to clamp down on this card here. You sure you have a good grip?" Meanwhile, as the right hand is holding the card that you are, his left hand is setting up a pinky break so when he switches cards, the double lift he uses is nearly impossible to spot. With time and experience, a good card handler will boggle your mind.
So, being an illusionist, how would David Blaine go about misdirecting judges attention to break a world record of holding his breath.....for 17min at that?