Sea turtles are large turtles that inhabit warm waters of the sea. They are similar to their terrestrial (land) cousins, the tortoises, and to freshwater turtles, except that their legs have been modified into flippers to aid them in swimming. They also cannot pull their heads and legs into their shells if threatened. There are six species of sea turtles that inhabit Indonesian waters: hawksbill, loggerhead, olive ridley, green, flatback, and leatherback.