The tale begins in the high halls of Asgard, where the trickster god Loki had found himself in a dire predicament. While flying in the form of a hawk, Loki had been captured by the giant Geirröðr, who held a deep-seated hatred for the Aesir. To win his freedom, Loki was forced to swear a binding oath: he would lure Thor to Geirröðr's courts without his powerful hammer, Mjölnir, his belt of strength, Megingjörð, or his iron gauntlets. Loki, ever the silver-tongued manipulator, convinced Thor to join him on a journey to the land of the giants under the guise of a diplomatic mission or a simple adventure, conveniently forgetting to mention the prohibition on Thor’s weapons. Thor, who often relied on his raw power and the companionship of Loki, agreed to the journey, leaving his most prized possessions behind in the safety of his palace, Bilskirnir.
As they traveled toward Jotunheim, the landscape shifted from the fertile lands of Midgard to the jagged, frost-bitten peaks and deep, shadowed valleys of the giants. Before reaching their destination, the duo stopped at the house of a giantess named Gríðr, known in some accounts as Grid. Unlike many of her kin, Grid was a friendly acquaintance of the gods—and notably, the mother of Odin's son Víðarr. Sensing the malice in Geirröðr’s intentions and knowing that Thor was walking into a trap unarmed, Grid provided him with her own magical artifacts. She lent him a pair of iron gloves, a belt of strength, and a powerful wooden staff known as Gríðarvölr. These items would prove essential for the trials to come, as Thor was not merely walking into a physical confrontation but a struggle against the very elements of nature that the giants commanded.
The most significant obstacle on their path was the mighty river Vimur, which in this telling is reflected in the powerful, surging currents of the Glomma in Norway. The Vimur was known to be the greatest of all rivers, its waters cold as the primordial ice of Niflheim and its currents strong enough to sweep away even the hardiest of travelers. When Thor and Loki arrived at its banks, the water seemed manageable at first. Thor, ever the resolute warrior, stepped into the water, bracing himself with the staff Gríðarvölr. Loki, fearing the depths, clung tightly to Thor’s belt as they began their crossing. However, as they reached the midpoint of the wide river, the water began to swell with unnatural speed. What was once a knee-high stream quickly rose to Thor’s waist, then to his shoulders, the churning white foam threatening to swallow Loki whole.
Thor looked upstream to find the cause of this sudden deluge. There, standing astride the river with one foot on each bank of a narrowing gorge, was the giantess Gjálp, the daughter of Geirröðr. She was massive and hideous, her eyes burning with a cruel light as she looked down at the god of thunder. It became clear that she was the source of the flood, pouring her own essence—some say urine, others say a magical torrent—directly into the stream to drown the Aesir before they could reach her father’s hall. The water roared with a deafening sound, and the footing beneath Thor’s feet became slick and unstable. The pressure of the current against his chest was immense, threatening to break even his god-like ribs. He realized then that he was not just fighting water, but the spite of the Jötnar made manifest.
In this moment of crisis, Thor did not panic. He looked up at Gjálp and shouted a proverb that has echoed through Norse lore: 'At ósi skal á stemma,' meaning 'A river must be dammed at its mouth' or 'at its source.' With a sudden burst of strength, he reached down and grabbed a massive stone from the riverbed. Using the iron gloves provided by Grid, he hurled the rock with the force of a thunderbolt. His aim was true, and the stone struck Gjálp directly, causing her to scream in pain and retreat from her position over the river. With the source of the flood interrupted, the water began to stabilize, though it was still a raging torrent that Thor had to navigate.
As Thor struggled to reach the far bank, he saw a rowan tree leaning over the water. Its branches were heavy with red berries, reaching out like a hand toward the drowning god. Grasping the wood firmly, Thor hauled himself and the shivering Loki out of the freezing depths. Because of this act of salvation, the rowan tree became known as 'Thor’s Salvation' (Þórsbjörg) in Norse tradition, forever sacred to those who seek protection from the elements. Once on dry land, Thor did not rest for long. His blood was up, and his resolve was hardened by the attempt on his life. He marched toward the hall of Geirröðr, the staff Gríðarvölr clicking against the stones of the giant’s mountain path like the first cracks of a coming storm.
Upon arriving at Geirröðr’s hall, the hospitality offered to them was as treacherous as the river crossing. Thor was led to a chamber and told to sit in a lone chair to rest. As soon as he sat down, he felt the chair begin to rise toward the ceiling. Looking up, he saw that the rafters were spiked with iron, and he realized that Gjálp and her sister Greip were hiding beneath the chair, pushing it upward with their massive backs to crush him against the roof. Thor acted instantly. He planted the staff Gríðarvölr against the ceiling and pushed down with all the might of his belt-enhanced strength. A sickening crack echoed through the hall as the backs of the two giantesses were broken under the pressure, ending their threat forever.