Niflheim, the "world of mist" or "world of fog", is the realm of ice, cold, and darkness in Norse cosmology, the frozen counterpart to the fiery Muspelheim, and one of the two elemental worlds that existed before the ordered cosmos. In the Eddic account of the beginning, Niflheim's freezing fogs filled the northern reaches, and where they met the sparks and heat of Muspelheim across the void of Ginnungagap, the ice thawed into the first life, the primordial giant Ymir and the cow Audhumla, so that the world is generated from the collision of the two extremes.
At its heart lies the spring Hvergelmir, the source of the cosmic rivers, from beneath one of the roots of the world-tree Yggdrasil, and the sources sometimes blur Niflheim with the realm of the dead (Niflhel, the misty Hel) in the cold depths below. Niflheim represents primal, undifferentiated cold and darkness, the negative pole of the Norse cosmos, present at the origin, out of whose meeting with its opposite all warmth, life, and order arose. It is the frozen matrix at the roots of the world.