The eldest spring in the world called Hvergelmir “bubbling boiling spring” is located in Niflheim and it is protected by the huge dragon called Nidhug (Old Norse: Níðhöggr).
It is said that all cold rivers come from the spring Hvergelmir, and it is said to be the source of the eleven rivers (Élivágar). The spring is the origin of all that is living and the place where every living being will go back.
The water from Élivágar flowed down the mountains to the plains of Ginnungagap, where it solidified to frost and ice, which gradually formed a very dense layer. As the world tree Yggdrasil started to grow, it stretched one of its three large roots far into Niflheim and drew water from the spring Hvergelmir.