Hvergelmir
Hvergelmir is the wellspring of cold in
Niflheim in
Norse mythology. The well is guarded by
Ivaldi and his sons who are charged with the defence of
Hel against the incursions of the storm giants. All cold rivers are said to come from here, and it was said to be the source of the eleven rivers, Elivagar. The name means approximately "The seething cauldron". Above the spring, the serpent
Nidhogg gnaws on one of the roots of the world ash,
Yggdrasil.