Word origin?

Yesterday I watched a segment from Wagner's Der Ring des Nibelungen. It refers to the realm of the Nibelungen as Nibelheim, a German variant of Old Norse niflheim. The Nordic myths always describe niflheim as dark and foggy, which got me wondering if maybe the German word for fog, Nebel, derives from this. Can anyone tell me if I'm onto something, or if I'm just making shit up?