The leatherback is the world's largest sea turtle, it has a carapace (shell) up to 2 m in length and can weigh a total of 0.5 tonnes. Characteristic features are a blackish leathery shell with 7 longitudinal ridges along the back, three of which are clearly visible when the animal is swimming at the surface. The skin is also black and relatively smooth with pale spotting. The leatherback is warm-blooded (endothermic), maintaining a body temperature of around 25 °C, which is unusual as most reptiles are cold-blooded (ectotherms).The leatherback is the sole living representative of the family Dermochelyidae. It is clear that the leatherbacks extensive migrations to British waters are to follow swarms of jellyfish which are the leatherbacks main prey item. Breeding occurs in shallow tropical waters, although female leatherbacks will come high up on the shore to deposit their eggs. Populations of leatherbacks are in serious decline due to a number of factors. These include loss of nesting habitats, destruction of nests by poachers, propeller wounds, interaction with commercial fisheries and ingestion of marine debris. 

Dermochelys coriacea is listed as Critically endangered on the Red list of Threatened animals 2000 and, therefore, considered to be of extremely high risk of extinction in the wild in the immediate future. It is listed under the UK Biodiversity Action Plan and is addressed under a marine turtles Species Action Plan. Dermochelys coriacia is listed on Appendix I of the Convention on the International Trade in Endangered Species of Flora and Fauna (CITES) 1975, Appendix II of the Bern Convention 1979, Appendices I and II of the Bonn Convention 1979 and Annex IV of the EC Habitats Directive. The loggerhead is also listed as a priority species on Annex II of the EC Habitats Directive. All five species are protected under Schedule 5 of the Wildlife and Countryside Act 1981 and the Conservation (Natural Habitats & c.) Regulations 1994 (Anon, 1999(ii)).