The olive ridley sea turtle (Lepidochelys olivacea), also known commonly as the Pacific ridley sea turtle, is a species of turtle in the family Cheloniidae. The species is the second-smallest and most abundant of all sea turtles found in the world. L. olivacea is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean. This turtle and the related Kemp's ridley turtle are best known for their unique synchronised mass nestings called arribadas, where thousands of females come together on the same beach to lay eggs. The olive ridley sea turtle may have been first described as Testudo mydas minor by Georg Adolf Suckow in 1798. It was later described and named Chelonia multiscutata by Heinrich Kuhl in 1820. Still later, it was described and named Chelonia olivacea by Johann Friedrich von Eschscholtz in 1829. The species was placed in the subgenus Lepidochelys by Leopold Fitzinger in 1843. After Lepidochelys was elevated to full genus status, the species was called Lepidochelys olivacea by Charles Frédéric Girard in 1858. Because Eschscholtz was the first to propose the specific epithet olivacea, he is credited as the binomial authority or taxon author in the valid name Lepidochelys olivacea (Eschscholtz, 1829). The parentheses indicate that the species was originally described in a different genus. The generic name, Lepidochelys, is derived from the Greek words lepidos, meaning scale, and chelys, which translates to turtle. This could possibly be a reference to the supernumerary costal scutes characteristic of this genus. The etymology of the English vernacular name "olive" is somewhat easier to resolve, as its carapace is olive green in color. However, the origin of "ridley" is unknown, perhaps derived from "riddle". Lepidochelys is the only genus of sea turtles containing more than one extant species: L. olivacea and the closely related L. kempii (Kemp's ridley).