Tortuguero, Costa Rica. Oct 11, 2010. A green sea turtle (Chelonia mydas) hatchling takes a leap of faith as it heads to the sea. An estimated 20 million hatchlings leave the Tortuguero National Park in Costa Rica each year. Only 1 in 1,000 will reach maturity but conservation efforts have allowed the nesting population to rebound 400% since 1959, when the Sea Turtle Conservancy was established.