I guess it depends. When we did the race, we were taken right to the start, shown the route map and told to leave our bags with the cruise staff girl in front of the map. The race began very quickly after that for us so we did not have time to buy the shirts before the race. But I am not sure if this is true for other people doing the race on other cruise stops in Castaway Cay. If you have someone who will be waiting at the finish for you, they can easily pick up the shirt while you are doing the race since the shirts are sold at the area close to the finish line. We didn't have anybody waiting for us as we were meeting the rest of our family on the beach when we were finished.