Scapa Flow is a body of water in the Orkney Islands, Scotland, sheltered by the islands of Mainland, Graemsay, Burray, South Ronaldsay and Hoy. Its sheltered waters have played an important role in travel, trade and conflict throughout the centuries. Vikings anchored their longships in Scapa Flow more than a thousand years ago. It was the United Kingdom's chief naval base during the First and Second World wars, but the facility was closed in 1956.

A roadstead or road is a body of water sheltered from rip currents, spring tides, or ocean swell where ships can lie reasonably safely at anchor without dragging or snatching. It can be open or natural, usually estuary-based, or may be created artificially. In maritime law, it is described as a "known general station for ships, notoriously used as such, and distinguished by the name".