What is the name of the well at the root of Yggdrasil guarded by Mimir?

The well at Yggdrasil’s root guarded by Mímir is Mímisbrunnr. Its name means “Mímir’s wellspring,” and it is associated with wisdom, intelligence, and profound knowledge.

In Snorri Sturluson’s Prose Edda, Mímisbrunnr lies beneath one of Yggdrasil’s three roots, the root extending toward the realm of the frost giants. Mímir, described as exceptionally wise, drinks from the well using the Gjallarhorn. Odin seeks a drink from its waters but must leave one of his eyes as a pledge before receiving it.

That eye sacrifice is one of the best-known stories in Norse mythology. It explains why Odin is associated not only with war and kingship but also with knowledge, poetry, magic, and runes. Mímir’s wisdom is so important that even after Mímir is beheaded in the conflict between the Æsir and Vanir, Odin preserves the head and consults it.

Mímisbrunnr is often confused with the other two wells beneath Yggdrasil: Hvergelmir, linked with Niflheim and Níðhöggr, and Urðarbrunnr, where the Norns shape destiny. Gjöll is a river, not Mímir’s well.