The Four Great Guardians of Iceland:
According to the Saga of King Olaf Tryggvason in Heimskringla, King Harald Bluetooth Gormsson of Denmark, intending to invade Iceland, had a wizard send his spirit out in the form of a whale to scout it out for points of vulnerability. Swimming westwards around the northern coast, the wizard saw that all the hillsides and hollows were full of landvættir, “some large and some small.”
He swam up Vopnafjörður, intending to go ashore, but a great dragon came flying down the valley toward him, followed by many snakes, insects, and lizards, all spitting poison at him.
“So he went back and continued around the coast westward to Eyjafjörður, where he again swam inland. This time he was met by a great bird, so big that its wings touched the hillsides on either side, with many other birds large and small following it.
“Retreating again and continuing west and south, he swam into Breiðafjörður. There he was met by a huge bull, bellowing horribly, with many landvættir following it.
“He retreated again, continued south around Reykjanes, and tried to come ashore at Vikarsskeið, but there he encountered a mountain giant (bergrisi), his head higher than the hill-tops, with an iron staff in his hand and followed by many other giants (jötnar). He continued along the south coast but saw nowhere else where a longship could put in, ‘nothing but sands and wasteland and high waves crashing on the shore.’
— Article on the Landvættir (“land wights”), via Wikipedia