Before Thor is humbled in the stronghold of Utgard, he meets on the road a giant so vast that the gods spend the night in his glove. Thor and Skrymir is the tale in which even the strongest of gods reaches his limits – and nothing is what it seems.
Thor, Loki and two human servants journey east into the giant-land of Jötunheim. In a forest they seek shelter and find a strange hall with a side-room. Only in the morning does it show itself: it was the mitten of a giant sleeper.
The giant is called Skrymir (‘big fellow’) and offers to travel with them. He carries everyone's provisions in his bag – but when they halt, Thor cannot undo the knot. In anger he strikes the sleeping giant three times on the head with Mjölnir. Each time Skrymir only wakes and asks whether a leaf or an acorn has fallen on his head. In the morning he parts from them – and only later does Thor grasp it: the blows had not struck the giant but a mountain, into which three deep valleys were hammered. Skrymir was an illusion, worked by Utgard-Loki himself.
“Art thou awake, Thor? Did a leaf fall from the tree upon my head?”after the Prose Edda (Snorri); public-domain tradition

Thor · Mjölnir – Thor's hammer · Jötunheim · The Norse pantheon · Midgard.
Snorri Sturluson, Gylfaginning (c. 1220); English public-domain Edda tradition: Henry Adams Bellows / Arthur G. Brodeur. Scholarship: Rudolf Simek, Dictionary of Northern Mythology; John Lindow, Norse Mythology.