arribada

:  the synchronized, large-scale nesting of some species of sea turtle (such as the Kemp’s ridley and olive ridley) During an arribada, hundreds of thousands of these 2-foot-long turtles (the smallest [sea turtles] in the world) gather off certain beaches, and over several days, come ashore to dig holes in the sand and lay eggs. — Susan Scott, Honolulu Star-Bulletin, 28 Sept. 2009 The arribada appears to be a behavior unique to the genus Lepidochelys, and the arribadas of olive ridleys are considered one of the wonders of the world. — Ann Barkau Meylan, Natural History, November 1986