Scapa Flow

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.

Scapa Flow has a shallow sandy bottom not deeper than 60 metres and most of it is about 30 m deep; it is one of the great natural harbours and anchorages of the world, with sufficient space to hold a number of navies. The harbour has an area of 324.5 square kilometres and contains just under 1 billion cubic metres of water.