Largest hardshell sea turtle

With a worldwide distribution, the largest species of hardshell sea turtle is the loggerhead sea turtle Caretta caretta. As a full-grown adult, its maximum recorded weight is 545 kg (with an average weight of 135 kg), and its maximum length can be up to 280 cm (its average length is 90 cm). In terms of average weight and length, the green turtle Chelonia mydas slightly exceeds the loggerhead, but its maximum recorded weight is only 395 kg and its maximum length only 153 cm (both measurements deriving from the same, exceptionally large specimen).

Only one species of sea turtle is larger than the loggerhead in absolute size, and that is the leathery or leatherback turtle Dermochelys coriacea, which is the only non-hardshell species of sea turtle alive today. Instead of possessing a single hard shell or carapace composed of large scutes, the leathery turtle has a thick rubbery or leathery ridged upper surface embedded with numerous tiny discrete bony structures known as osteoderms.