Olive Ridley Arribada — Ostional Costa Rica

Each month from July through December at Ostional beach in Costa Rica, hundreds of thousands of olive ridley sea turtles arrive simultaneously to nest in one of the world's most extraordinary wildlife spectacles — the mass nesting event called an arribada, when the beach becomes so densely packed with nesting turtles that arriving females climb over nesting females, digging up previously laid eggs in their urgency to deposit their own. The Ostional arribada is the largest in the world for olive ridley turtles, with a single three-to-five day event involving 200,000 to 500,000 females turning the beach into a writhing carpet of turtles visible from the air as a moving grey-green mass from horizon to horizon. The community of Ostional has a unique and scientifically managed arrangement allowing local harvesting of eggs from the earliest arribada days when most would be destroyed by subsequent nesters, combining conservation with community livelihoods in a model studied worldwide. Watching a turtle emerge from the surf at midnight, excavate her nest with methodical flipper strokes while completely ignoring the observer just one metre away, and deposit 100 eggs before covering them and returning to the Pacific creates an intimacy of encounter with the tidal rhythm of life that is one of the most moving experiences in wildlife travel. Dawn arrives on an Ostional beach to reveal a tableau of hundreds of turtles simultaneously in various stages of nesting.