The Presentation Sisters have confirmed that two of their nuns drowned at Inch Beach in Co Kerry last night.
They have been named as Sr Imelda Carew and Sr Paula Buckley - both from Dublin.
The nuns, who were 67 and 70, were observed by a lifeguard getting into difficulties shortly after 7pm last night and a rescue operation was immediately mounted.
They were taken from the water by the Valentia Coastguard and airlifted to Tralee Hospital where they were later pronounced dead.
Gardaí confirmed later that night that the two women had been declared dead.
The nuns' order has issued a statement saying: "It is with great regret that we confirm the deaths of Sr Imelda Carew and Sr Paula Buckley, members of the South East Province of the Presentation Sisters of the Blessed Virgin Mary following a tragic drowning accident in Kerry on Thursday, 14 August.
"The sisters were on holiday in Kerry and got into difficulties during an early evening swim at Inch Strand."
The South East Province stretches from Dublin, south of the Liffey to Wexford and across to Hospital, Co Limerick.
It encompasses the dioceses of Cashel and Emly, Ossory, Waterford and Lismore, Ferns and some of the diocese of Dublin.
Congregational Leader of the Presentation Sisters Union, Sr Mary Deane, said: "We are all stunned and shocked by this tragedy. Words seem inadequate to express our loss and sorrow as we come to terms with the tragic events that unfolded on a beautiful sunny evening.
"It is a tragic loss for all of us and for their families. These two wonderful women have been a source of inspiration and blessing to many people throughout their lives. Our thoughts and prayers are with the families, communities and friends of our beloved Sisters at this time."