"Lake of the Monster"
Whereas some lakes have traditions of killer otters or amphibious equines, the creatures spotted from time to time in Lough Abisdealy (which in Irish supposedly translates as "Lake of the Monster") of County Cork are described as giant sized eels. But before being identified as such, several characteristics of this large serpentine beast only serve to divorce them from any Anguilla relation.
It was most likely the Loch Ness Monster hype at the time that inspired author Edith Somerville to include a lake monster sighting from Cork in her book The Smile and the Tear. The lough had already a reputation of being the haunt of a dreadful sheep-devouring "worm" when in January of 1914, the beast appeared before three locals headed for Church.
I do not know which of the little party first saw the snake, but they all agreed that suddenly they beheld a long black creature propelling itself rapidly across the lake. Its flat head, on a long neck, was held high, two great loops of its length buckled in and out of the water as it progressed. Obviously a snake, and a huge one. The three witnesses stared, doubtful of their own eyes at this amazing sight. The avenue is within a few yards of the water, so they were able to have a clear view of the mysterious monster. For how long they gazed at it I do not know. Unfortunately a virtuous anxiety not to keep her scholars waiting induced the principal witness to proceed on the way to church before the snake submerged. But her certainty that it was a snake, and a very large one, could not be shaken.
The witness estimated the animal had a length of 35 feet. A monstrous snake is out of the question for obvious reasons but could it have been an enormous eel? The most significant detail of this account lies in the creatures movements. The "loops" and "buckling" movement suggests undulation (a trait found primarily in mammals) as opposed to the side to side weaving motions of an eel. However, undulation, or the seemingly appearance of, does not necessarily disqualify reptile or fish as candidates. The swimming movements of anacondas have sometimes been described as up and down rather than side to side. Not suggesting the snake is actually able to contort its spine in such a vertical fashion but rather that the surfacing body parts appear in a particular aligned formation which creates the illusion of humps rising and descending. The same impression might be cast by an equally large eel. Nevertheless, the only way this would create loops would be if the animal were somehow swimming on its side and surely the observer would haven taken note of such an abstract spectacle.
The eel likeness is extended to a land observation from the lake. Very late one moonlit night, a man driving home in his horse-drawn cart saw what looked like a huge eel crawling out of the water. The locals had always maintained that in the lough lived an eel the size of a man's thigh.
Peter Costello's In Search of Lake Monsters citing: Edith Somerville, The Smile and the Tear
A final report comes from Dr. Roy Mackal's The Monsters of Loch Ness. A dark brown object was seeing swing parts of its body above the surface of the lough in two foot arches. It was "exactly like the tail end of a huge conger eel."
Dr. Roy Mackal The Monsters of Loch Ness, citing Teige O'Donovan