There are 16 inhabited islands and collectively they are known as Orkney.

The largest of the Orkneys, which lie off the north coast of Scotland, is Orkney mainland, which was originally known as "Hrossey" (from the Norse for Horse Island). Orkney's principal island is now referred to as "Mainland". The erroneous name "Pomona" can still sometimes be seen on the occasional modern map but this stems from a 17th Century cartographical error and has never been used by Orcadians. The Orkney Mainland is divided between Kirkwall and Scapa into two sectors, known locally as the East Mainland and West Mainland.

Surrounding mainland Orkney is a chain of smaller islands, namely Burray, Eday, Egilsay, Flotta, Graemsay, Holms of Stromness, North Ronaldsay, Papa Westray, Rousay, Sanday, Shapinsay, South Ronaldsay, Stronsay, Westray and Wyre.

Flotta overlooks Scapa Flow, the scene of the German High Fleet scuttling at the end of the First World War. The island was a strategic military base in two World Wars, and latterly as the location for an oil terminal which has helped keep Orkney's economy afloat.