Orkney was the site of a Royal Navy base at Scapa Flow, which played a major role in World War I and II. After the Armistice in 1918, the German High Seas Fleet was transferred in its entirety to Scapa Flow to await a decision on its future. The German sailors opened the seacocks and scuttled all the ships. Most ships were salvaged, but the remaining wrecks are now a favoured haunt of recreational divers. One month into World War II, a German U-boat sank the Royal Navy battleship in Scapa Flow. As a result, barriers were built to close most of the access channels; these had the additional advantage of creating causeways enabling travellers to go from island to island by road instead of being obliged to rely on ferries. The causeways were constructed by Italian prisoners of war, who also constructed the ornate Italian Chapel.