If Lough Ree was a hotbed for water monster reports it's only natural to suspect its southern kin, Lough Derg, has its own wealth of stories.
The 1960 sighting by the priests on Lough Ree created a sort of "safe haven" for otherwise who had otherwise been silent about their experiences with strange things in the lake to finally step forward. However, it would appear this inviting atmosphere did not trickle too far down the Shannon since over the years very few sightings from Derg have been recorded (at least, according to our present knowledge anyway.)
Kilgarvan Quay, near Ballinderry 1978
Issue 41 of the British Columbia Scientific Cryptozoology Club's Quarterly (a newsletter issued to members of the BCSCC) ran a three page article on Irish lake monsters written by David Ll. Davies. Davies, a man of Irish descent himself, took a look at Irish reports from Peter Costello's In Search of Lake Monsters along with the aid of visiting friend Peter Glanville, who had recently graduated from University College of Dublin with a specialty in Physical Geography. With Costello's book and Peter's knowledge of Ireland's geographical history and characteristics, the two poured over maps looking for any patterns or clues connecting reports. During the course of their examination David writes that once they began looking at reports from the Shannon River, Peter recalled a childhood incident that had taken place on Lough Derg while with his family.
The Glanvilles had a cottage on the northeastern shore of Lough Derg and owned a dingy which they used to cruise about the lake as well as other parts of the Shannon. One day in 1978 while on the dingy together with his mother and two sisters, Peter's mother caught sight of something large in the water. Seemingly alive and as it was quite large, the object inspired Mrs. Glanvilles into rowing "as fast as she could" to shore.
David was able to provide the contents of a letter from Mrs. Jane Glanville in which she gave a statement on the sighting.
One spring evening when out rowing with the children, I saw a large shape which appeared to be moving across the water behind the boat. I was scared that something of that size might upset the dinghy and the water was still very cold for small children to swim in. Exactly, what I saw I am not sure about. It had three humps moving simultaneously so it was unlikely to be three fish swimming together. It could have been a very large pike, but I have never seen anything like this before or since. It was about six feet long from end to end. By the time we had reached the Quay it had disappeared. I have a good recollection of the "thing" but what I actually saw I am not sure about. Some people seem to think it was a very large salmon, but I prefer to refer to the "Lough Derg Monster."
In the summer of 2000, Chad Arment received an email in regards to his website [now Strangeark.com] asking for his opinion on an interesting sight had by a young visitor to Lough Derg. After establishing contact with the witness through Chad, the individual provided this account:
It was a clear brisk day (when is it not?) and we were well out into the Loch. Mr. Dolan had cut the engine and asked if we'd rather fish or continue the boat ride. I looked over the edge of the boat and saw how clear and deep the water was and it kind of gave me the willies to look so far down. Within that moment an enormous God-knows-what swam aside the boat from my back to my front and was easily the length of the boat (12 feet). It was very pale and uniform in color. Whitey looking. Unfortunately my shock was so complete I didn't note fins, flippers etc. I do remember that I didn't see the head and that it turned toward the boat after swimming aside it. It was underwater completely and maybe a foot of water was above it. It did swim deeper when it turned. It would've bumped the boat otherwise.
The closest thing I can come up with is a Beluga whale.
1981 Lionel Leslie Expedition
While info on Derg sightings is presently limited, Captain Lionel Leslie apparently had enough reports to inspire him to launch an expedition in 1981. At one point during the operation his made sonar contact with a large object, which he concluded to be an unknown animal. Leslie wrote book afterwards on his lake monster studies but publication was halted by his sudden death not long after the book's completion. What possible new information Captain Leslie was prepared to offer regarding Lough Derg remains unknown until this manuscript can hopefully be recovered.