The attractively wooded island in the lake is believed to have been a crannog or lake-dwelling.
The ruin of an old castle still stands upon the island.
This is Knockalough Castle, one of the castles of Turlogh Roe Mac Mahon, a chieftain well known by tradition as "Turlogh Roe, the liar and deceiver, who by one stroke killed his wife and child".
In the townland of Knockalough the big event of the year in the early 1900's was the "races". These races attracted huge crowds of spectators, hawkers and traders from all over West Clare.
Reference: http://www.clarelibrary.ie/eolas/coclare/places/kilmihilvisit.htm