Yggdrasil: The World Tree Explained

Yggdrasil is the immense ash tree at the center of the Norse cosmos, the world-tree whose branches spread over every world and whose three roots reach down to the wells of fate, wisdom and primal cold. The gods ride to it every day to hold their court, the Norns water it from the Well of Urðr, and a dragon, an eagle, a squirrel and four stags live on and under it. The Eddic poem Völuspá says it shudders when Ragnarök begins, but no source says that it falls.

Yggdrasil quick facts

What is Yggdrasil?

Yggdrasil is the world-tree, the living structure that holds the Norse cosmos together. In Grímnismál, Odin ranks it the foremost of trees, as Sleipnir is the best of horses. Snorri Sturluson, the 13th-century Icelandic Christian who systematized the myths in his Prose Edda, says in Gylfaginning that its limbs spread over the whole world and stand above the sky.

It is also the gods' courthouse. Snorri says the Æsir ride over the bridge Bifröst each day to hold judgment at the Well of Urðr beneath one root. Grímnismál adds that Thor must wade there through rivers instead, because the gods' bridge burns all aflame.

Völuspá describes the ash as "sprinkled with white clay," the source of the dews that fall in the valleys, standing "ever green" over Urðr's well. Snorri explains the clay: the Norns mix it with water from the well every day and pour it over the tree so its branches do not wither or rot. The dew that falls from it, he adds, is honeydew, and bees feed on it.

What does the name mean? The common scholarly reading takes Yggr, "the terrible one," as a name of Odin and drasill as a poetic word for horse. "Odin's horse" would be a kenning for the gallows, which the hanged man "rides," pointing at Odin's ordeal on the tree. Other proposals read "terror tree" or derive the name from a word for yew. No medieval source explains it.

Why did Odin hang on Yggdrasil?

Odin hung on the tree to win the runes, the secret knowledge of writing and magic. In Hávamál 138-141 he tells it in the first person: he hung on a windy tree for nine full nights, wounded with a spear and "given to Odin, myself to myself," on a tree of which no one knows from what roots it rises. No one gave him bread or a drink from the horn. He peered downward, took up the runes, screaming as he took them, and fell back.

Afterward, the poem says, he learned nine mighty songs from the son of Bölþorn, Bestla's father (Snorri makes Bestla Odin's mother, so this is Odin's uncle), won a drink of the precious mead from Óðrerir, and began to flourish and grow wise, one word leading him to the next.

Hávamál never actually names the tree. The identification with Yggdrasil rests on the name "Odin's horse" and the tree of unknown roots; most scholars accept it, but it is an inference. The ordeal pairs with Odin's other price for knowledge, the eye he pledged in Mímir's well under another root (Völuspá, Gylfaginning).

What are the nine realms?

The nine realms are the worlds of the Norse cosmos, but no medieval source lists all nine. Völuspá opens with the seeress remembering "nine worlds" and a glorious tree beneath the earth; the giant Vafþrúðnir, in Vafþrúðnismál, boasts of visiting nine worlds below Niflhel; Snorri says Odin gave Hel authority over nine worlds. None names them.

The list most often given today is:

• Asgard — the Æsir
• Vanaheim — the Vanir
• Álfheim — the elves (in Grímnismál, given to the god Freyr)
• Midgard — humans
• Jötunheim — the giants
• Svartálfaheim or Niðavellir — dwarves and dark elves
• Niflheim — mist and ice
• Muspelheim — fire
• Hel — the dead

Each name appears somewhere in the Eddas, but the set of nine is a modern reconstruction from scattered mentions, not a list from any ancient text.

What the sources do show is a cosmos of travel. Thor walks into giant country again and again, and Hermóðr rides nine nights down and north to Hel to beg for Baldur's return. The layout is roughly vertical, never a tidy diagram. For the Greek contrast, see Norse vs Greek Gods: Key Differences.

What are the three wells?

The three wells are Urðarbrunnr, Mímisbrunnr and Hvergelmir, and in Snorri's Gylfaginning each lies under one of Yggdrasil's three roots.

• Urðarbrunnr, the Well of Urðr. Under the root in heaven among the Æsir, where the gods hold court. Snorri says its water turns everything in it as white as the membrane inside an eggshell, and two swans feed there. In Völuspá the three Norns — Urðr, Verðandi and Skuld — come from this water to lay down laws and choose lives.
• Mímisbrunnr, Mímir's well. Under the root toward the frost giants. Wisdom is hidden in it; Snorri says its keeper Mímir drinks from it with the horn Gjallarhorn, and Odin got a drink only by pledging an eye. Völuspá has Mímir drink mead each morning from Odin's pledge instead.
• Hvergelmir. Under the root over Niflheim, the world of mist and cold. Snorri calls it the spring of Niflheim's rivers; the dragon Níðhöggr gnaws the root from below among countless serpents.

Grímnismál pictures the roots differently: Hel lives under one, the frost giants under the second, humankind under the third. That stanza mentions no wells, and only the frost giants appear in both lists.

What creatures live in Yggdrasil?

Yggdrasil is home to an eagle, a hawk, a squirrel, a dragon, four stags and many serpents, and most of them are harming it.

• The eagle. Unnamed; Snorri says it knows many things.
• Veðrfölnir. A hawk that sits between the eagle's eyes. Only Snorri names it.
• Ratatoskr. A squirrel that runs up and down the trunk. In Grímnismál it carries the eagle's words down to Níðhöggr; Snorri adds that it carries words of envy between the two.
• Níðhöggr. A dragon (its name is usually read as "malice-striker") that gnaws the root over Niflheim. In Völuspá it also sucks the corpses of the dead in Náströnd, the shore of corpses.
• Four stags. Dáinn, Dvalinn, Duneyrr and Duraþrór bite the highest shoots, according to Grímnismál; Snorri has them run among the branches eating the leaves.
• Serpents. More lie under the ash than any fool imagines, says Grímnismál, naming six: Góinn, Móinn, Grábakr, Grafvölluðr, Ófnir and Sváfnir.

Grímnismál sums it up: the ash suffers more than people know, with a stag biting above, rot on its side and Níðhöggr cutting below. In Snorri's account, only the Norns' daily watering keeps its branches from rotting.

What happens to Yggdrasil at Ragnarök?

At Ragnarök Yggdrasil shudders and groans, but the sources never say that it falls or burns. In Völuspá, as the final crisis begins, "Yggdrasil's ash shakes where it stands, the old tree groans, and the giant breaks free" — usually read as Loki escaping his bonds. Snorri's Gylfaginning repeats it: the ash trembles, and nothing in heaven or on earth is without fear.

Then the sun turns black, the earth sinks into the sea and fire plays against the sky itself. Völuspá describes a green earth rising again but never mentions Yggdrasil in it.

One detail hints at survival. Vafþrúðnismál, repeated by Snorri, says two humans, Líf and Lífþrasir, will hide in Hoddmímir's holt (a wood), live on morning dew and repopulate the world. Many scholars identify that wood with Yggdrasil, partly through the link to Mímir, but no source says so.

Völuspá ends on an unsettling image: after the renewal, the dark dragon Níðhöggr comes flying up from the dark hills below, bearing corpses in its feathers. The full sequence of the end is in Ragnarök: Every Event, In Order.

In the sources

• Völuspá (Poetic Edda) — the nine worlds, the evergreen ash over Urðr's well, the Norns, Odin's eye in Mímir's well, the tree shuddering at Ragnarök and Níðhöggr's final flight.
• Grímnismál (Poetic Edda) — the fullest catalog: the gods' daily ride to judgment, the three roots, Ratatoskr, the stags, the serpents and the tree's suffering.
• Hávamál (Poetic Edda) — Odin's nine nights on the windy tree and his winning of the runes.
• Vafþrúðnismál (Poetic Edda) — the nine worlds below Niflhel and the survivors Líf and Lífþrasir in Hoddmímir's holt.
• Snorri Sturluson's Prose Edda, Gylfaginning — the systematized account: roots and wells, the eagle and Veðrfölnir, the Norns' care, the honeydew and Ragnarök.

The Eddic poems survive mainly in the 13th-century Codex Regius. Snorri, a Christian writing in the same century, drew on them and often quotes them.

Contradictions to flag:

• What lies under the roots. Snorri says the Æsir, the frost giants and Niflheim; Grímnismál says Hel, the frost giants and humankind. Snorri even calls the heavenly root the "third" after already listing a different third.
• Mímir's drink. Snorri has Mímir drink from his well with the Gjallarhorn; Völuspá has him drink mead each morning from Odin's pledge, usually read as the eye.
• The nine realms. Three sources mention nine worlds; none lists them.
• Odin's tree. Hávamál never names Yggdrasil. The identification rests on the name "Odin's horse."
• The tree's survival. No source says Yggdrasil burns or survives; equating it with Hoddmímir's holt is a scholarly inference.

In popular culture

• Marvel. The first Thor film (2011) shows Yggdrasil as a cosmic tree linking the Nine Realms, closer to a star map than to the Eddic ash.
• God of War (2018) and God of War Ragnarök (2022). The games make the World Tree a travel network between realms and Ratatoskr a talking, bad-tempered character. His personality is invented; his go-between role comes from Grímnismál and Snorri.
• Wagner. In the prologue to Götterdämmerung, the Norns recall that Wotan broke a branch from the World Ash for his spear and the tree withered. That story is Wagner's invention.

Keep exploring

The Norns who water the tree shape every fate in it — meet them in The Norns: Norse Fate and Why It Can't Be Escaped. And the roots reach down to the realm of the dead, ruled by Hel: Ruler of the Norse Underworld. Then see how much of the Norse cosmos you remember with the Norse mythology quiz.