These Scapa flow at the heart of the Orkney archipelago is a deep water body which is home to many scuttled German WWI battleships.
These scuttled ships and those like them are the primary source of low-background steel. Low-background steel is any steel produced prior to the detonation of the first atomic bombs in the 1940s and 1950s. With the Trinity test and the Atomic bombing of Hiroshima and Nagasaki in 1945, and then subsequent nuclear weapons testing during the early years of the Cold War, background radiation levels increased across the world. Modern steel is contaminated with radionuclides because its production used atmospheric air. Low background steel is so called because it does not suffer from such nuclear contamination. This steel is used in devices that require the highest sensitivity for detecting radionuclides including scientific instruments that are sent into space and Geiger counters.