The Athlanmarans can survive at great depths in the sea by magic but Sperm whales are the real life deep divers. Sperm whales are one of the largest of the whales. They have been known to dive as deep as a mile under the surface and stay down for 2 hours at a time. The whales eat many kinds of squid and fish including the Giant and Colossal Squid. The Sperm whale has many biological adaptations to deal with the intense pressures deep under the surface of the ocean.
One problem with the intense pressures is that air cavities inside of their bodies, like sinuses and the middle ear, could explode. Sperm whales have lots of blood vessels in these cavities and when they dive the vessels fill up displacing the air. Another problem with diving deep is the air in their lungs. The whales have a collapsible rib cage to get air away from their aveoli. This also prevents nitrogen from entering their blood stream which would give them the bends when they surface. The third problem Sperm whales have to overcome is the lack of oxygen on the long dives. To combat this the whales have 2 to 3 times the blood volume of humans, 2 times the hemoglobin, which transports oxygen, and 10 times the myoglobin, which stores oxygen in muscles. These amazing animals are specifically designed to be the deep diving champs of the sea!