No one should visit Boyle and its grand ruins and not see the two very beautiful lakes that are near it, Loch Key and Loch Arrow. Loch Key is not over a mile from the town, and Loch Arrow not more than three. The very fine domain of Rockingham may be said to be almost surrounded by Loch Key. It was on an island in this lake that the McDermotts, chieftains of Moylurg, had a stronghold. The island has a castle on it at present, but, seen from the shore, both island and castle appear very small. The fortress the McDermotts had on the island must have been a sort of _crannióg_, or wooden castle, like so many that have been discovered both in Ireland and Scotland in the tracks of dried-up lakes. Those _cranniógs_ were sometimes built entirely on piles, and sometimes on islands, with extensions on piles if the water was not too deep. This last must have been the kind of fortress the McDermotts had on Loch Key, for it must have been much larger than the present island, and must have been large enough to give space to a multitude of people to assemble on it. We read in the annals of Loch Key of the following awful catastrophe that happened on it in 1184: "The Rock of Loch Key was burned by lightning--_i.e._, the very magnificent, kingly residence of the Muintir Maolruanaigh (the McDermotts) where neither goods nor people of all that were there found protection; where six or seven score of distinguished persons were destroyed, along with fifteen men of the race of kings and chieftains, with the wife of McDermott ... and every one of them who was not burned was drowned in that tumultuous consternation in the entrance of the place; so that there escaped not alive therefrom but Connor McDermott with a very small number of the multitude of his people." The same catastrophe is mentioned by the Four Masters, but under the year 1187. This account of the burning of the castle, or, as the annalist calls it, a residence, shows that it was a wooden structure, for it would hardly have been possible to burn a building of stone so quickly that the people in it would not have had time to escape, even if it were on an island.