Hawksbill sea turtle (Eretmochelys imbricata) silhouette
  All sea turtles are air breathers requiring them to breath-hold the entire time they are underwater. Their physiology is well adapted to the marine environment thus allowing them to stay submerged for sustainable periods of time. While active, a hawksbill sea turtle was recorded staying submerged for 56 minutes. While inactive (ie. sleeping), sea turtles have been recorded to last from 2 to 5 hours on a single breath of air.