Turtles sleep on the surface while in deep water or under a rocky areas. Many divers have found green turtles sleeping on reefs.
All sea turtles drink only seawater all of their lives. They have special glands behind each eye, called "salt glands" that they use to get rid of all the salt from the seawater.
70% of the oxygen comes from the ocean. Reefs are the most important part of the ocean and without them, marine life would die. No coral reefs, means no oxygen from the ocean.
Algae living in the coral reef also produces oxygen.