How to bring out pumped BM for when traveling

Hi mummies, I'm a first time mummy and I want to know how do i bring out my pumped breast milks when traveling out to make sure they don't spoil. Usually once pumped, it can only be out in room temperature for about 3 hours. What if I'm traveling long hours? How do I store my breast milk to feed my baby?#firstbaby #pleasehelp #1stimemom #advicepls