Scapa Flow is a natural harbour surrounded by the Scottish Orkney Islands. In response to the build-up of the German Imperial Navy's High Seas Fleet and before the outbreak of the First World War, the British decided that it would be the home of their Grand Fleet. Despite its strategic importance it was not a safe anchorage. Bad weather, strong tides and the many entrances to Scapa Flow made it vulnerable. Coastal batteries, minefields, anti-submarine obstacles and boom defences were constructed to defend the fleet. Blockships were sunk to seal the many entrances to Scapa Flow and prevent access to enemy ships.
The First World War proved that Scapa Flow was a good choice. In 1916 the Grand Fleet intercepted an outbreak of the German High Seas Fleet and the Battle of Jutland followed. It became the greatest naval battle in history. The outcome of the battle was indecisive but the High Seas Fleet would never leave their harbour again and the British Royal Navy maintained their superiority.
After the war the British fleet left Scapa Flow, but in 1933 the political situation in Europe was getting worse. Scapa Flow became once again the home of the British fleet. At the beginning of the Second World War the old defences had fallen in disrepair. On 14 October 1939 the German U-boat U-47 penetrated Scapa Flow and sank the battleship HMS Royal Oak. 833 of the crew were lost. After this incident Scapa Flow became one of the most strongly fortified harbours in the world.
After the war the British fleet left Scapa Flow for good. The last facilities were closed down in 1956. What remains are the remnants in the landscape of this once great harbour.