Leatherback turtles can be found primarily in the open ocean. Scientists tracked a leatherback turtle that swam from Indonesia to the U.S. in an epic 20,000 km (12,000 mi) foraging journey over a period of 647 days. Leatherbacks follow their jellyfish prey throughout the day, resulting in turtles "preferring" deeper water in the daytime, and shallower water at night (when the jellyfish rise up the water column). This hunting strategy often places turtles in very frigid waters. One individual was found actively hunting in waters that had a surface temperature of 0.4 °C. Leatherback turtles are known to pursue prey deeper than 1000 m — beyond the physiological limits of all other diving animals except for beaked whales and sperm whales.Its favored breeding beaches are mainland sites facing deep water, and they seem to avoid those sites protected by coral reefs.