I think it depends on which ship. Radiance pools are heated, Serenade is not. Both ships have the covered Solarium pool, which is usually only for adults (over 16), but on the cold weather routes they usually open the Solarium up to everyone at least for part of the day. Still...there should be plenty to keep them busy no matter what! My kids have been on all classes of Royal ships from the giant Allure to the much smaller ships and to date, their favorite has been the older, smaller Rhapsody. They felt like the staff worked super hard to keep them busy and having fun since there were not all the bells and whistles of the bigger ships.