He pre-breathes 100% oxygen for up to 30 minutes prior to the breathhold: https://en.wikipedia.org/wiki/Static_apnea#With_pure_oxygen https://en.wikipedia.org/w

He pre-breathes 100% oxygen for up to 30 minutes prior to the breathhold: https://en.wikipedia.org/wiki/Static_apnea#With_pure_oxygen https://en.wikipedia.org/wiki/Static_apnea#With_pure_oxygen World record without this trick is 11 min 54.