Leatherback Sea Turtle

Rather than use a high resting metabolism, leatherbacks appear to take advantages of a high activity rate. Studies on wild D.coriacea discovered individuals may spend as little as 0.1% of the day resting. This constant swimming creates muscle-derived heat. Coupled with their counter-current heat exchangers, insulating fat covering and large size, leatherbacks are able to maintain high temperature differentials compared to the surrounding water. Adult leatherbacks have been found with core body temperatures that were 18 °C (32.4 °F) above the water they were swimming in.
Leatherback turtles are one of the deepest diving marine animals. Individuals have been recorded diving to depths as great as 1,280 metres (4,200 ft). Typical dive durations are between 3 and 8 minutes, with dives of 30–70 minutes occurring infrequently.
They are also the fastest-moving reptiles. The 1992 edition of the Guinness Book of World Records lists the leatherback turtle moving at 35.28 kilometres per hour (21.92 mph) in the water. More typically, they swim at 0.5–2.8 metres per second (1.1–6.3 mph).