Leviathan was a sea monster referred to in the Old Testament. The word Leviathan has become synonymous with any large sea monster or creature.
According to legend, the Leviathan was a fire-breathing creature of such immense size that the sea boils when it swims to the surface. It ruthlessly and fearlessly rules over all the other creatures of the sea. The Leviathan's skin is like a double coat of mail, with overlapping scales the size of shields on its back, and as sharp and hard as broken pottery on its under-parts. Swords and harpoons will simply bounce off such protection. It breathes smoke from its nostrils and flames from its mouth which is rimmed with sharp teeth. Its fins radiate a brilliant light and its eyes are like the glimmerings of dawn.