Scapa Flow (Old Norse: Skalpaflói) is a body of water in the Orkney Islands, north of Scotland. It is sheltered by the islands of Mainland, Graemsay, Burray, South Ronaldsay and Hoy. At 140 square miles, with a sandy bottom, and relatively shallow (not deeper than 160 feet, and most of it about 70 feet deep), it is one of the great natural harbours/anchorages of the world, with sufficient space to hold a number of navies. The vikings used the body of water to anchor their ships on their way to raiding the lands further south.
Scapa Flow is an epicenter of magical activity, with many sites of power and ancient henges nearby. For this reason, a Hermetic Covenant, also called Scapa Flow, was founded on Hoy in 821, claiming all of the Orkneys.