The teen was one of three swimmers who went missing in Annaghmore Lough near Strokestown yesterday evening.
Two of the swimmers managed to reach the shore, but the body of this third was recovered before midnight by a search party led by the Irish Coast Guard's Shannon rescue helicopter and involving local angling boats.
The sad news comes just a day after a 12-year-old boy drowned while swimming in the sea off Youghal beach in Co Cork.
That followed the death of a 21-year-old woman named Lisa Knight who was swimming with friends in the River Feale in Co Limerick late on Tuesday night.
And on Wednesday afternoon a 17-year-old boy drowned after getting into difficulty swimming in a lake in Celbridge, Co Kildare, according to The Irish Times.
Irish Water Safety chief John Leech has appealed to the public on RTÉ Radio 1's Morning Ireland to be aware of the risks associated with the water, especially in unsupervised areas - and particularly for inexperienced swimmers.