The gods had arranged a lavish feast with Aegir and Ran, two gracious and hospitable giants who dwell beneath the sea. Aegir and Ran offered to host the banquet, but only if the gods could provide them with a kettle big enough to brew mead for all of the invited guests. The gods knew that, of all the beings in the Nine Worlds, only the giant Hymir possessed a cauldron large enough for this purpose. Thor, the brawniest and bravest of the gods, as well as the one most accustomed to dealing with the giants – not all of whom are as friendly to the gods as are Aegir and Ran – volunteered to obtain this cauldron from Hymir.
Upon the god’s arrival at his house, Hymir slaughtered three bulls for provisions for the two during Thor’s stay. The giant was shocked and dismayed, however, when Thor ate two of the bulls in one sitting to assuage his legendary hunger. Because of this, the angry giant declared, they would need to go fishing in the morning for the next day’s food.
In the morning, Hymir sent Thor to procure bait for their hooks. Thor went to Hymir’s pastures and slaughtered the biggest of the giant’s remaining bulls, intending to use the head as bait. Hymir was now more irritated than ever at the rash youngster, but hoped his strength and daring would be of help on their fishing trip.
The two got into the boat, with Thor in the stern. The god rowed them out to Hymir’s usual fishing grounds, where the giant, to his delight, caught two whales. But then, Thor began to row the boat further out from land. His companion grew fearful and demanded that they row back at once, “because,” he reminded Thor, “Jormungand lurks below these wild waves.” Thor, the age-old enemy of that monstrous sea serpent, refused.
At last, Thor dropped the oars and cast his line into the water. After an ominous silence and calm, Thor felt a mighty tug on his line. As he reeled it in, a violent rumbling shook the boat and whipped the waves. The giant grew pale with terror, but Thor persisted. His feet were planted so firmly in the bottom of the boat that the planks gave way and water began pouring in.
When the serpent’s head, with the hook in his venom-dripping mouth, at last came up above the water, Thor reached for his hammer. At this moment, Hymir panicked and cut the line. The howling snake slunk back down into the ocean. Thor, enraged at having missed this opportunity to end his greatest foe, heaved Hymir overboard.
Thor, with the two whales slung over his shoulders, waded back to land, picked up Hymir’s cauldron, and returned home to Asgard.
Looking for more great information on Norse mythology and religion? While this site provides the ultimate online introduction to the topic, my book The Viking Spirit provides the ultimate introduction to Norse mythology and religion period. I’ve also written a popular list of The 10 Best Norse Mythology Books, which you’ll probably find helpful in your pursuit.
 The Poetic Edda. Hymiskviða.
 Snorri Sturluson. The Prose Edda. Gylfaginning 48.