Information available for Orkney is presented as ten area summaries: South Sanday/ Deer Sound/ Scapa Flow/ South West Mainland/ Hoy Sound and Bring Deeps/ Eyenhallow, Wyre and Rousay Sounds/ Wide Firth and Shapinsay Sound/ Papa Westray/ Eday Sound/ North Sanday. Each area is described in a standard format, giving details of its physical and biological character, the marine biotopes present and their distribution, the sites surveyed, current nature conservation designations, the main human influences and relevant literature.