Every year, at the same place and time, thousands of female Kemp's ridley sea turtles (Lepidochelys kempii) come ashore to nest and lay their eggs on the beach. This mass nesting event is known as an arribada, meaning “arrival by sea” in Spanish. Scientists didn't know where kemp's ridleys nested until the late 1940's, when a filmmaker filmed more than 40,000 turtles coming ashore to nest on the same night in Rancho Nuevo, Mexico. Today, however, far fewer Kemp's ridleys come ashore to nest; in 2011, when this photo was taken, just 20,000 nests were found in Mexico, and 81 percent of those were at Rancho Nuevo. Read more at the Ocean Portal blog.