The giant leatherback sea turtle, Dermochelys coriacea, is the biggest turtle species still in the world. In addition to being very large, one thing that is immediately noticeable is that they don’t possess a bony shell, like most other turtle species. They are instead covered in a thick layer of “leather” and fat, hence their name — the Giant Leatherback Turtle. They have what is considered to be the most hydrodynamic body design of any living turtle, which is part of what allows them to reach speeds of up to 22 mph, making them the fastest moving reptile in the world.
On average Dermochelys coriacea adults tend towards around 6.0–7.2 feet in total length, and towards a weight of around 550 to 1,500 lbs. They can reach much, much larger than that though. The biggest one reported in modern times was over 9.8 feet when measured from head to tail, with a carapace longer than 7.2 feet, and weighing in at about 2,000 lbs. That individual was found on a beach on the west coast of Wales.