It's maybe worth keeping in mind that Ireland was neutral in WWII. I guess that the belligerents still lost many ships in Irish waters (and indeed Irish ships were often attacked: https://en.wikipedia.org/wiki/Irish_neutrality_during_World_... ), but it's still some important context.
Probably the most famous wartime loss was the Lusitania off the Old Head of Kinsale. Its fame is partly that it was a Cunard ship like the Titanic, and partly because of the controversy around her cargo. Although it was a passenger liner, it was sunk by a German U-Boat because it was thought to be smuggling arms from the then-neutral US to England.
https://en.wikipedia.org/wiki/RMS_Lusitania