The arrival of many Olive ridley sea turtles (Lepidochelys olivacea) at the beach of Ostional, Costa Rica, Pacific coast, at the beginning of an arribada (mass nesting event) November ^^^ Thousands and thousands of the 50 kilogram reptiles come ashore over a period of up to a week, only interrupted by the hottest midday sun, to bury their eggs in the warm sand.