The Leatherback is the biggest of the sea turtles and his name derives from the fact that he has a leathery, soft scale in contrast to the other sea turtles, who have hard scales. With a length up to 185 centimetres and a weight up to 700 kilograms it is an impressive creature. It is also the sea turtle that has the biggest habitat and is found in almost every ocean on the planet and lays eggs on the shores of every continent except Antarctica. Because the Leatherback spends most of it’s time in very deep water, most of its behaviour is unknown. Only for nesting the Leatherbacks leave their deep sea environment, where they can reach depths of more than one kilometre. The primary food source for the Leatherback sea turtle is jellyfish. It still is mystery how the Leatherback sea turtles can navigate in open sea, since they have limited vision and there are no visual anchor points to give direction. One of the theories is that the sea turtles use the earth’s magnetic field or use the position of the moon to navigate. After a short mating period the female Leatherback sea turtle is ready to nest and chooses a beach close to deeper water such as Parismina, Tortuguero or Gandoca to lay her eggs. But also on the Pacific coast in the Province of Guanacaste on Playa Grande and on the beaches of the National Park Las Baulas Leatherbacks arrive. The Leatherback sea turtle digs a hole of more than 60 centimetres and can lay eighty to one hundred eggs. Afterwards the nest is carefully camouflaged and sometimes even fake nests are made to mislead predators. The young turtles break the eggshell with a special temporary tooth and crawl to the surface to start their run for the sea. It is calculated that only one in thousand will reach adulthood. This statistic is a delicate balance that has been reached over the more than 110 million years that the sea turtles exist. The balance has been abruptly destroyed by humans who considered the eggs as a delicacy and aphrodisiac. Combined with the pollution of the oceans with plastic that the Leatherbacks mistake for jellyfish, it has resulted in the fact that the Leatherback sea turtle is the most endangered specie with an estimated population of no more than 35,000 individuals. Although the northern part of the Caribbean coast of the Province of Limon is the most famous for the arrival of the sea turtles, the less known Gandoca beach hosts between 500 and 1,000 nests. The Leatherback sea turtles arrive in the months of March to July. Costa Rica’s government has stimulated awareness programs for sustainable development, which has resulted in many initiatives to save the endangered sea turtles. After six years of the project in Gandoca the survival rate of sea turtle nests improved from 5 to 95%.