According to Live Science, not all kinds of turtles can do that. These species have developed ways to pick up oxygen even when submerged. They can nestle down underwater and slow their metabolism down so much they barely need any oxygen.
Under water, turtles drop their internal temperatures, shrink their metabolisms and stop using their summer lungs to breathe in the oxygen they need to keep themselves alive. The colder they make themselves, the less they need oxygen.
They can then take a small amount of water into their cloaca – which is the all-in-one opening reptiles have for defecation, urination, reproduction, and egg laying – and absorb the air in the water, then expel it and take in another small amount.
