To investigate the distribution and migrations of sea turtles occurring in Korean waters, an adult female green sea turtle Chelonia mydas was tagged with a satellite transmitter and released at Busan in October 2009. The confirmation was made for the first time that the released green sea turtle migrated back to Korea after visiting Jeju Island and Japan for approximately 9 months. The green sea turtle spent the winter in Jeju and Japan because of low water temperatures in the East Sea and South Sea during winter months, which were not suitable for turtle survival. Compared with an immature green sea turtle that was released at Jeju Island, the adult green showed a markedly different migration pattern, suggesting that juvenile and adult greens move differently because of their peculiar life cycle and their stage of maturity, in addition to responses to temperature changes. Additional satellite tracking with increased representation of species, sexes and sizes of turtles, and regions is required to gather information on the distribution and movements of sea turtles in Korean waters.