Hi, Carol!
The ETA you’re mentioning is related to travel to the UK, not the US, and from what you’ve described, it doesn’t seem to be part of your itinerary.
If you were wondering about Northern Ireland, you can enter freely with an Irish passport under the Common Travel Area, so no ETA is needed there either. You can find more information about the
ETA system here.
For peace of mind, and especially if your cruise has stops in different countries, it’s always best to double-check entry requirements directly with the cruise company, as they’ll confirm exactly what documents you need for each stop.
Enjoy the trip, Alaska sounds amazing! 😀