The Nordland Line, the longest in Norway. Stretching between Trondheim and Bodo, it was first built to transport the country's iron ore. When first constructed, it was the northernmost railway line on Earth, and today its locomotives are among the most powerful ever built. But its secret story remains hidden at the bottom of a nearby fjord, where the wrecks of Nazi destroyers and Allied ships lay testament to the crucial role it played in WWII.