Far in the north of the world-order, in icy remoteness, lies Niflheim – the ‘mist-home’. Here reign cold, frost and everlasting twilight. It is one of the two primal worlds, and from its meeting with fire life first arose.
The name comes from Old Norse nifl – ‘mist, fog, darkness’ (cognate with German Nebel). Niflheim is the cold counterpart to fiery Muspelheim; between the two yawned, at the beginning, the primal void Ginnungagap.
In Niflheim rises the spring Hvergelmir (‘the roaring kettle’), from which all the rivers of the world flow – including the icy Élivágar. When their spray met the fire of Muspelheim, the rime melted and formed the primal giant Ymir. Beneath one of the roots of the world-tree Yggdrasil lies Hvergelmir, and there the dragon Nidhögg gnaws at the root among countless serpents.
“Hvergelmir it is called, whence come all waters, / and take their way from thence.”after Grímnismál 26, translation in the Bellows tradition (public domain)

Ginnungagap – the yawning void · Muspelheim – the fire world · Ymir · Yggdrasil · Helheim.
Snorri Sturluson, Gylfaginning (c. 1220). Grímnismál, Völuspá (Poetic Edda), English public domain: Henry Adams Bellows (1923). Scholarship: Rudolf Simek, Dictionary of Northern Mythology; John Lindow, Norse Mythology.