NiflheimOn the lowest level was Niflheim, the Land of the Dead. It was a gloomy place of ice, snow and eternal darkness. It was ruled by Hel, the gruesome Queen of the Dead. To reach Niflheim you had to travel for nine days northwards and downwards from Midgard. At the gate waited the ghastly dog, Garm, with his bloodstained breast.
Niflheim ("House of Mists") is the far northern region of icy fogs and mists, darkness and cold. It is situated on the lowest level of the universe. The realm of death, Helheim is part of the vast, cold region. Niflheim lies underneath the third root of Yggdrasil, close to the spring Hvergelmir ("Roaring Cauldron"). Also situated on this level is Nastrond, the Shore of Corpses, where the serpent Nidhogg eats corpses and gnaws on the roots of Yggdrasil.
After Ragnarok, there will be a hall here for the punishment of murderers, oath breakers, and philanderers.
Hel or Helheim ("House of Hel", Realm of the dead) is known to be a part of Niflheim. This cold, dark and misty abode of the dead is also ruled by Hel, the monstrous daughter of the trickster god Loki and his wife Angrboda.
No one can ever leave this place, because of the impassable river Gjoll that flows from the spring Hvergelmir and encircles Helheim. Once they enter Helheim, not even the gods can leave. Those who die of old age or disease, and those not killed in battle, go to Helheim while those who die bravely on the battlefield go to Valhalla.
The entrance to Helheim is guarded by Garm, a monstrous hound, and Modgud. The giant Hraesvelg ("corpse eater") sits at the edge of the world, overlooking Helheim. In the form of an eagle with flapping wings he makes the wind blow.
MuspellThe fires of Muspell (also known as Muspellheim) burned on this level too. Muspell ("Home of Desolation") is a flaming, torrid region, the land of fire far to the south. It is opposed to Niflheim and whose animating beams made the ice in Niflheim melt and created the first living beings. The celestial bodies were made from its sparks which flew out into space. Muspell is ruled by the fire giant Surt, whose wife is Sinmore. Muspell was guarded by Surt and his flaming sword. He was waiting to lead the fiery creatures of Muspell against the gods when the time come for their downfall.
Ginnungagap ("Seeming Emptiness"), in the cosmology of Norse mythology, is the primordial void separating Niflheim and Muspell, the land of eternal ice and snow and the land of eternal heat and flame.
In the beginning, before the world of men and gods existed, the spring Hvergelmir, deep in the frozen wastes of Niflheim, gave rise to eleven rivers known as the Elivagar. Over a long period of time, water of the Elivagar ran across Niflheim and poured into the northern part of Ginnungagap. The water froze, forming vast sheets of ice in the void. Hot air from Muspell melted some of the ice, creating a zone of meltwater amid the ice and snow. Here life began, and the first living thing was a frost giant called Ymir.