Hvergelmir

In Norse mythology, Hvergelmir (Old Norse "bubbling boiling spring") is a major spring. Hvergelmir is attested in the Poetic Edda, compiled in the 13th century from earlier traditional sources, and the Prose Edda, written in the 13th century by Snorri Sturluson. In the Poetic Edda, Hvergelmir is mentioned in a single stanza, which details that it is the location where liquid from the antlers of the stag Eikþyrnir flow, and that the spring, "whence all waters rise", is the source of numerous rivers. The Prose Edda repeats this information and adds that the spring is located in Niflheim, that it is one of the three major springs at the primary roots of the cosmic tree Yggdrasil (the other two are Urðarbrunnr and Mímisbrunnr), and that within the spring are a vast amount of snakes and the dragon Níðhöggr.

Hvergelmir is attested in the following works:

Hvergelmir receives a single mention in the Poetic Edda, found in the poem Grímnismál:

This stanza is followed by three stanzas consisting mainly of the names of 42 rivers. Some of these rivers lead to the dwelling of the gods (such as Gömul and Geirvimul), while at least two (Gjöll and Leipt), reach to Hel.

Hvergelmir is mentioned several times in the Prose Edda. In Gylfaginning, Just-as-High explains that the spring Hvergelmir is located in the foggy realm of Niflheim: "It was many ages before the earth was created that Niflheim was made, and in its midst lies a spring called Hvergelmir, and from it flows the rivers called Svol, Gunnthra, Fiorm, Fimbulthul, Slidr and Hrid, Sylg and Ylg, Vid, Leiptr; Gioll is next to Hell-gates."

...
Wikipedia