Whales appeared in most medieval literature as one of nature's hatred creatures either malevolent themselves or controlled by evil forces and people. There's no surprise then, that Icelandic Folklore has dedicated many a legend to the illhveli, the wicked whales, populating the Artic Ocean.
The King's Mirror (record published ca. 1250) contains the oldest summary known in the Nordic language of the names and descriptions of the whales known to humans in the Icelandic seas at that time. The katthveli, meaning Cat Whale, is among them, marked as one of the wicked whales cruising the oceans.
Described as having the shape of a bulky seal, short dolphin, or stocky whale, this whale is said to have strong forequarters and narrower hindquarters, with the mouth of a cat, the strength of a bear, and the hunger of a wolf.
However, its name mostly comes from the presence of long whiskers on its snout and the sounds it makes, similar to a very loud purr when it exhales, to mews and hisses when agitated or on the hunt.
Compare to other illhveli, the Katthveli is fairly small, with a maximum length of 8 m. But, what it lacks in size, it makes in ferocity. According to Saint Brendan (i.e, also referred to as The Voyager or The Navigator, one of the early Irish Saints and one of the Twelve Apostles of Ireland) this whale had a mouth filled with short, sharp teeth, mostly protruding from its upper jaw, while the adults grew large horn-like protuberances resembling elongated boar’s tusks.
When hunting, the katthveli's eyes gleam brazenly and its flippers, large and strong, ending in nasty hooked claws, slash left and right, cutting through boats' hulls and whales bellies without alike. They present in a variety of colors, including pink, grey, and peaty brown. One of the most detailed records of an encounter with a katthveli comes from the Faroe Islands, where witnesses descrive the color of the whale as pale under the chin and with woolly skin.
These whales are cruel and vicious, using their speed and agility to swim underneath boats and flip them. Once, a katthveli chased a boat off the Skálanesbjarg cliffs (east Iceland), but gave up after it was the rowers, in a supreme effort, managed to overtake it and leave it behind. Another of these whales intercepted a ship at Héradsflói Bay (eastern Iceland) and swam alongside it, preventing the sailors from fishing and following them with its eyes. Desperated, the sailor thought of harpooning the intruder, but the idea was ruled out as nobody wanted to provoke it. Eventually, perhaps out of boredom, the whale dove and disappeared.
Off Seley Island (a little island off the west coast of Iceland), Ásmundur Helgason and his crew were attacked by a large katthvely. The beast rammed their boat and stuck its head through the hull. After a terrifying struggle, they managed to push it out and make for safety despite the damage. In Faroese waters, a katthveli reared out of the water and put its flippers on the gunwale of a boat, hissing and spitting like a cat and snapping at the sailors until one man put his gun in its mouth and fired. Badly wounded, perhaps dead, the animal slid off into the depths.
At times, katthvelis seek to move unnoticed, traveling among groups of rorquals (i.e., baleen whales) or schools of large fish.
In the bay of a small island, St. Brendan encountered what he called a large sea-cat, the size of a horse, that had originally been brought as a pup along with twelve pilgrim sailors. It was quite friendly and tame, he wrote, but soon grew bigger and hungrier and eventually ate all but one of the sailors, who took refuge in a small stone church. St. Brendan prayed for aid, and immediately a great whale lunged out of the sea and seized the sea-cat, pulling it into the sea where they both drowned each other.
-Jón Baldur Hlíðberg, Sigurður Ægisson. 2008. Meeting with Monsters: An Illustrated Guide to the Beasts of Iceland. JPV.
-Szabo, V.E., 2008. Chapter Six. From Krakens To Fish Drivers: Monstrous Fishes In North Atlantic History And Literature. In Monstrous Fishes and the Mead-Dark Sea (pp. 177-210). BRILL.
-Einarsson, N., 1996. A sea of images: fishers, whalers and environmentalists. Images of contemporary Iceland: everyday lives and global contexts, pp.46-59.
-Joensen, J. P. Tradition and Changes in the Concepts of Water-Beings in Faroese Folklore. 1996. Islanders and Water-Dwellers. Proceedings of the Celtic-Nordic-Baltic Folklore Symposium, DBA Publications.