Besides the U boat that dropped survivors in Kerry early on in the war, there is not one recorded incident of a U boat in Irish waters, except as figment of the imagination of the Daily Express/Mail.
Well one that was going to Irish waters was carrying Sean Russell back from Germany after his liaison with the Nazis. I would be very surprised if that was the only one tbh.
Also
During this patrol, U-38 was able to land Walter Simon, a Nazi agent, at Dingle Bay in Ireland on June 12. Not realising that the passenger services of the Tralee and Dingle Light Railway had been closed fourteen months earlier, he asked when the next train to Dublin was. He was arrested and interned in the Curragh Camp for the duration of the war.