Navy SEALs will be able to hold their breath for 4 hours

the PopMechanics Brain Trust : scientist
Advances in nanotechnology will help us overcome not only illness but also the limits of being human. For example, robotic red blood cells called respirocytes could each hold 200 times the oxygen of their natural counterparts, enabling a man on a mission to, say, hide out underwater for half a day without a scuba tank

Popular mechanics, (2012) "110 Predictions For the Next 110 Years", [online], Available: