The World Serpent

Norse mythology places Jörmungandr in the ocean as a child, grown until it circled the world and bit its own tail. Thor hooks it once, in a tale of a fishing trip with an ox-head for bait, and has it breaking the surface before his terrified companion cuts the line. The two are promised to each other. At the end, the sources say, Thor will kill the serpent and walk nine paces from its body before the venom takes him. He is described as knowing this. He goes fishing anyway.