Some women exclusively pump and/or overproduce.
Although I have not experienced this on the cruise ship, when staying in hotels I’ve cooled in bags on ice or ice packs and then once/day traded supplies for staff to put in a freezer used for guest medical supplies. The fridge on wonder wmshould work well enough as a “cooler.” Then just deposit milk once a day?
Flying with breast milk actually isn’t complicated, ESPECIALLY if you have the little one in tow.